#!/usr/bin/perl -w

=head1 NAME

parallel - build and execute shell command lines from standard input in parallel

=head1 SYNOPSIS

B<parallel> [options] [I<command> [arguments]] [< list_of_arguments]

=head1 DESCRIPTION

GNU B<parallel> is a shell tool for executing jobs in parallel locally
or using remote computers. A job is typically a single command or a
small script that has to be run for each of the lines in the
input. The typical input is a list of files, a list of hosts, a list
of users, a list of URLs, or a list of tables.

If you use B<xargs> today you will find GNU B<parallel> very easy to
use as GNU B<parallel> is written to have the same options as
B<xargs>. If you write loops in shell, you will find GNU B<parallel>
may be able to replace most of the loops and make them run faster by
running several jobs in parallel. If you use B<ppss> or B<pexec> you will find
GNU B<parallel> will often make the command easier to read.

GNU B<parallel> makes sure output from the commands is the same output as
you would get had you run the commands sequentially. This makes it
possible to use output from GNU B<parallel> as input for other programs.

For each line of input GNU B<parallel> will execute I<command> with
the line as arguments. If no I<command> is given, the line of input is
executed. Several lines will be run in parallel. GNU B<parallel> can
often be used as a substitute for B<xargs> or B<cat | bash>.

Before looking at the options you may want to check out the examples
after the list of options. That will give you an idea of what GNU
B<parallel> is capable of.

You can also watch the intro video for a quick introduction:
http://www.youtube.com/watch?v=LlXDtd_pRaY

=head1 OPTIONS

=over 9

=item I<command>

Command to execute.  If I<command> or the following arguments contain
{} every instance will be substituted with the input line. Setting a
command also invokes B<-f>.

If I<command> is given, GNU B<parallel> will behave similar to B<xargs>. If
I<command> is not given GNU B<parallel> will behave similar to B<cat | sh>.


=item B<{}>

Input line. This is the default replacement string and will normally
be used for putting the argument in the command line. It can be
changed with B<-I>.


=item B<{.}>

Input line without extension. This is a specialized replacement string
with the extension removed. If the input line contains B<.> after the
last B</> the last B<.> till the end of the string will be removed and
B<{.}> will be replaced with the remaining. E.g. I<foo.jpg> becomes
I<foo>, I<subdir/foo.jpg> becomes I<subdir/foo>, I<sub.dir/foo.jpg>
becomes I<sub.dir/foo>, I<sub.dir/bar> remains I<sub.dir/bar>. If the
input line does not contain B<.> it will remain unchanged.

B<{.}> can be used the same places as B<{}>. The replacement string
B<{.}> can be changed with B<-U>.


=item B<--null>

=item B<-0>

Use NUL as delimiter.  Normally input lines will end in \n
(newline). If they end in \0 (NUL), then use this option. It is useful
for processing arguments that may contain \n (newline).


=item B<--arg-file> I<input-file>

=item B<-a> I<input-file>

Read items from the file I<input-file> instead of standard input.  If
you use this option, stdin is given to the first process run.
Otherwise, stdin is redirected from /dev/null.


=item B<--basefile> I<file> (beta testing)

=item B<-B> I<file> (beta testing)

I<file> will be transferred to each sshlogin before a jobs is
started. It will be removed if B<--cleanup> is active. The file may be
a script to run or some common base data needed for the jobs.
Multiple B<-B> can be specified to transfer more basefiles. The
I<file> will be transferred the same way as B<--transfer>.


=item B<--cleanup>

Remove transferred files. B<--cleanup> will remove the transferred files
on the remote server after processing is done.

  find log -name '*gz' | parallel \
    --sshlogin server.example.com --transfer --return {.}.bz2 \
    --cleanup "zcat {} | bzip -9 >{.}.bz2"

With B<--transfer> the file transferred to the remote server will be
removed on the remote server.  Directories created will not be removed
- even if they are empty.

With B<--return> the file transferred from the remote server will be
removed on the remote server.  Directories created will not be removed
- even if they are empty.

B<--cleanup> is ignored when not used with B<--transfer> or B<--return>.


=item B<--command>

=item B<-c>

Line is a command.  The input line contains more than one argument or
the input line needs to be evaluated by the shell. This is the default
if I<command> is not set. Can be reversed with B<-f>.


=item B<--delimiter> I<delim>

=item B<-d> I<delim>

Input items are terminated by the specified character.  Quotes and
backslash are not special; every character in the input is taken
literally.  Disables the end-of-file string, which is treated like any
other argument.  This can be used when the input consists of simply
newline-separated items, although it is almost always better to design
your program to use --null where this is possible.  The specified
delimiter may be a single character, a C-style character escape such
as \n, or an octal or hexadecimal escape code.  Octal and
hexadecimal escape codes are understood as for the printf command.
Multibyte characters are not supported.

=item B<-E> I<eof-str>

Set the end of file string to eof-str.  If the end of file string
occurs as a line of input, the rest of the input is ignored.  If
neither B<-E> nor B<-e> is used, no end of file string is used.


=item B<--eof>[=I<eof-str>]

=item B<-e>[I<eof-str>]

This option is a synonym for the B<-E> option.  Use B<-E> instead,
because it is POSIX compliant for B<xargs> while this option is not.
If I<eof-str> is omitted, there is no end of file string.  If neither
B<-E> nor B<-e> is used, no end of file string is used.


=item B<--file>

=item B<-f>

Line is a filename.  The input line contains a filename that will be
quoted so it is not evaluated by the shell. This is the default if
I<command> is set. Can be reversed with B<-c>.


=item B<--group>

=item B<-g>

Group output.  Output from each jobs is grouped together and is only
printed when the command is finished. STDERR first followed by STDOUT.
B<-g> is the default. Can be reversed with B<-u>.

=item B<--help>

=item B<-h>

Print a summary of the options to GNU B<parallel> and exit.


=item B<--halt-on-error> <0|1|2> (beta testing)

=item B<-H> <0|1|2> (beta testing)

=over 3

=item 0

Do not halt if a job fails. Exit status will be the number of jobs
failed. This is the default.

=item 1

Do not start new jobs if a job fails, but complete the running jobs
including cleanup. The exit status will be the exit status from the
last failing job.

=item 2

Kill off all jobs immediately and exit without cleanup. The exit
status will be the exit status from the failing job.

=back


=item B<-I> I<replace-str>

Use the replacement string I<replace-str> instead of {}.


=item B<--replace>[=I<replace-str>]

=item B<-i>[I<replace-str>]

This option is a synonym for B<-I>I<replace-str> if I<replace-str> is
specified, and for B<-I>{} otherwise.  This option is deprecated;
use B<-I> instead.


=item B<--jobs> I<N>

=item B<-j> I<N>

=item B<--max-procs> I<N>

=item B<-P> I<N>

Run up to N jobs in parallel.  0 means as many as possible. Default is 9.


=item B<--jobs> I<+N>

=item B<-j> I<+N>

=item B<--max-procs> I<+N>

=item B<-P> I<+N>

Add N to the number of CPU cores.  Run this many jobs in parallel. For
compute intensive jobs B<-j> +0 is useful as it will run
number-of-cpu-cores jobs in parallel. See also
B<--use-cpus-instead-of-cores>.


=item B<--jobs> I<-N>

=item B<-j> I<-N>

=item B<--max-procs> I<-N>

=item B<-P> I<-N>

Subtract N from the number of CPU cores.  Run this many jobs in parallel.
If the evaluated number is less than 1 then 1 will be used.  See also
B<--use-cpus-instead-of-cores>.


=item B<--jobs> I<N>%

=item B<-j> I<N>%

=item B<--max-procs> I<N>%

=item B<-P> I<N>%

Multiply N% with the number of CPU cores.  Run this many jobs in parallel.
If the evaluated number is less than 1 then 1 will be used.  See also
B<--use-cpus-instead-of-cores>.


=item B<--keeporder>

=item B<-k>

Keep sequence of output same as the order of input. If jobs 1 2 3 4
end in the sequence 3 1 4 2 the output will still be 1 2 3 4.


=item B<-L> I<max-lines>

Use at most I<max-lines> nonblank input lines per command line.
Trailing blanks cause an input line to be logically continued on the
next input line.  Implies B<-x>.


=item B<--max-lines>[=I<max-lines>]

=item B<-l>[I<max-lines>]

Synonym for the B<-L> option.  Unlike B<-L>, the I<max-lines> argument
is optional.  If I<max-lines> is not specified, it defaults to one.
The B<-l> option is deprecated since the POSIX standard specifies
B<-L> instead.


=item B<--controlmaster> (experimental)

=item B<-M> (experimental)

Use ssh's ControlMaster to make ssh connections faster. Useful if jobs
run remote and are very fast to run. This is disabled for sshlogins
that specify their own ssh command.


=item B<--progress>

Show progress of computations. List the computers involved in the task
with number of CPU cores detected and the max number of jobs to
run. After that show progress for each computer: number of running
jobs, number of completed jobs, and percentage of all jobs done by
this computer. The percentage will only be available after all jobs
have been scheduled as GNU B<parallel> only read the next job when
ready to schedule it - this is to avoid wasting time and memory by
reading everything at startup.

By sending GNU B<parallel> SIGUSR2 you can toggle turning on/off
B<--progress> on a running GNU B<parallel> process.


=item B<--max-args>=I<max-args>

=item B<-n> I<max-args>

Use at most I<max-args> arguments per command line.  Fewer than
I<max-args> arguments will be used if the size (see the B<-s> option)
is exceeded, unless the B<-x> option is given, in which case
GNU B<parallel> will exit.

Only used with B<-m> and B<-X>.


=item B<--max-line-length-allowed>

Print the maximal number characters allowed on the command line and
exit (used by GNU B<parallel> itself to determine the line length
on remote computers).


=item B<--number-of-cpus>

Print the number of physical CPUs and exit (used by GNU B<parallel>
itself to determine the number of physical CPUs on remote computers).


=item B<--number-of-cores>

Print the number of CPU cores and exit (used by GNU B<parallel> itself
to determine the number of CPU cores on remote computers).


=item B<--interactive>

=item B<-p>

Prompt the user about whether to run each command line and read a line
from the terminal.  Only run the command line if the response starts
with 'y' or 'Y'.  Implies B<-t>.


=item B<--quote>

=item B<-q>

Quote I<command>.  This will quote the command line so special
characters are not interpreted by the shell. See the section
QUOTING. Most people will never need this.  Quoting is disabled by
default.


=item B<--no-run-if-empty>

=item B<-r>

If the standard input only contains whitespace, do not run the command.

=item B<--return> I<filename>

Transfer files from remote servers. B<--return> is used with
B<--sshlogin> when the arguments are files on the remote servers. When
processing is done the file I<filename> will be transferred
from the remote server using B<rsync> and will be put relative to
the default login dir. E.g.

  echo foo/bar.txt | parallel \
    --sshlogin server.example.com --return {.}.out touch {.}.out

This will transfer the file I<$HOME/foo/bar.out> from the server
I<server.example.com> to the file I<foo/bar.out> after running
B<touch foo/bar.out> on I<server.example.com>.

  echo /tmp/foo/bar.txt | parallel \
    --sshlogin server.example.com --return {.}.out touch {.}.out

This will transfer the file I</tmp/foo/bar.out> from the server
I<server.example.com> to the file I</tmp/foo/bar.out> after running
B<touch /tmp/foo/bar.out> on I<server.example.com>.

Multiple files can be transferred by repeating the options multiple
times:

  echo /tmp/foo/bar.txt | \
    parallel --sshlogin server.example.com \
    --return {.}.out --return {.}.out2 touch {.}.out {.}.out2

B<--return> is often used with B<--transfer> and B<--cleanup>.

B<--return> is ignored when used with B<--sshlogin :> or when not used
with B<--sshlogin>.


=item B<--max-chars>=I<max-chars>

=item B<-s> I<max-chars>

Use at most I<max-chars> characters per command line, including the
command and initial-arguments and the terminating nulls at the ends of
the argument strings.  The largest allowed value is system-dependent,
and is calculated as the argument length limit for exec, less the size
of your environment.  The default value is the maximum.


=item B<--show-limits>

Display the limits on the command-line length which are imposed by the
operating system and the B<-s> option.  Pipe the input from /dev/null
(and perhaps specify --no-run-if-empty) if you don't want GNU B<parallel>
to do anything.


=item B<-S> I<[ncpu/]sshlogin[,[ncpu/]sshlogin[,...]]> (beta testing)

=item B<--sshlogin> I<[ncpu/]sshlogin[,[ncpu/]sshlogin[,...]]> (beta testing)

Distribute jobs to remote servers. The jobs will be run on a list of
remote servers.  GNU B<parallel> will determine the number of CPU
cores on the remote servers and run the number of jobs as specified by
B<-j>.  If the number I<ncpu> is given GNU B<parallel> will use this
number for number of CPU cores on the host. Normally I<ncpu> will not
be needed.

An I<sshlogin> is of the form:

  [sshcommand [options]][username@]hostname

The sshlogin must not require a password.

The sshlogin ':' is special, it means 'no ssh' and will therefore run
on the local computer.

To specify more sshlogins separate the sshlogins by comma or repeat
the options multiple times.

For examples: see B<--sshloginfile>.

The remote host must have GNU B<parallel> installed.

B<--sshlogin> is known to cause problems with B<-m> and B<-X>.


=item B<--sshloginfile> I<filename> (beta testing)

File with sshlogins. The file consists of sshlogins on separate
lines. Empty lines and lines starting with '#' are ignored. Example:

  server.example.com
  username@server2.example.com
  8/my-8-core-server.example.com
  2/my_other_username@my-dualcore.example.net
  # This server has SSH running on port 2222
  ssh -p 2222 server.example.net
  4/ssh -p 2222 quadserver.example.net
  # Use a different ssh program
  myssh -p 2222 -l myusername hexacpu.example.net
  # Use a different ssh program with default number of cores
  //usr/local/bin/myssh -p 2222 -l myusername hexacpu.example.net
  # Use a different ssh program with 6 cores
  6//usr/local/bin/myssh -p 2222 -l myusername hexacpu.example.net
  # Assume 16 cores on the local computer
  16/:

When using a different ssh program the last argument must be the hostname.


=item B<--silent>

Silent.  The job to be run will not be printed. This is the default.
Can be reversed with B<-v>.


=item B<--verbose>

=item B<-t>

Print the command line on the standard error output before executing
it.

See also B<-v>.


=item B<--transfer>

Transfer files to remote servers. B<--transfer> is used with
B<--sshlogin> when the arguments are files and should be transferred to
the remote servers. The files will be transferred using B<rsync> and
will be put relative to the default login dir. E.g.

  echo foo/bar.txt | parallel \
    --sshlogin server.example.com --transfer wc

This will transfer the file I<foo/bar.txt> to the server
I<server.example.com> to the file I<$HOME/foo/bar.txt> before running
B<wc foo/bar.txt> on I<server.example.com>.

  echo /tmp/foo/bar.txt | parallel \
    --sshlogin server.example.com --transfer wc

This will transfer the file I<foo/bar.txt> to the server
I<server.example.com> to the file I</tmp/foo/bar.txt> before running
B<wc /tmp/foo/bar.txt> on I<server.example.com>.

B<--transfer> is often used with B<--return> and B<--cleanup>.

B<--transfer> is ignored when used with B<--sshlogin :> or when not used with B<--sshlogin>.


=item B<--trc> I<filename>

Transfer, Return, Cleanup. Short hand for:

B<--transfer> B<--return> I<filename> B<--cleanup>


=item B<--ungroup>

=item B<-u>

Ungroup output.  Output is printed as soon as possible. This may cause
output from different commands to be mixed. GNU B<parallel> runs
faster with B<-u>. Can be reversed with B<-g>.


=item B<--extensionreplace> I<replace-str>

=item B<-U> I<replace-str>

Use the replacement string I<replace-str> instead of {.} for input line without extension.


=item B<--use-cpus-instead-of-cores>

Count the number of physical CPUs instead of CPU cores. When computing
how many jobs to run in parallel relative to the number of CPU cores
you can ask GNU B<parallel> to instead look at the number of physical
CPUs. This will make sense for computers that have hyperthreading as
two jobs running on one CPU with hyperthreading will run slower than
two jobs running on two physical CPUs. Some multi-core CPUs can run
faster if only one thread is running per physical CPU. Most users will
not need this option.


=item B<-v>

Verbose.  Print the job to be run on STDOUT. Can be reversed with
B<--silent>. See also B<-t>.


=item B<--version>

=item B<-V>

Print the version GNU B<parallel> and exit.


=item B<--xargs>

=item B<-m>

Multiple. Insert as many arguments as the command line length
permits. If B<{}> is not used the arguments will be appended to the
line.  If B<{}> is used multiple times each B<{}> will be replaced
with all the arguments.

Support for B<-m> with B<--sshlogin> is limited and may fail.


=item B<-X>

xargs with context replace. This works like B<-m> except if B<{}> is part
of a word (like I<pic{}.jpg>) then the whole word will be
repeated. Normally B<-X> will do the right thing, whereas B<-m> can
give surprising results if B<{}> is used as part of a word.

Support for B<-X> with B<--sshlogin> is limited and may fail.


=item B<--exit>

=item B<-x>

Exit if the size (see the B<-s> option) is exceeded.


=back

=head1 EXAMPLE: Working as xargs -n1. Argument appending

GNU B<parallel> can work similar to B<xargs -n1>.

To compress all html files using B<gzip> run:

B<find . -name '*.html' | parallel gzip>


=head1 EXAMPLE: Inserting multiple arguments

When moving a lot of files like this: B<mv * destdir> you will
sometimes get the error:

B<bash: /bin/mv: Argument list too long>

because there are too many files. You can instead do:

B<ls | parallel mv {} destdir>

This will run B<mv> for each file. It can be done faster if B<mv> gets
as many arguments that will fit on the line:

B<ls | parallel -m mv {} destdir>


=head1 EXAMPLE: Context replace

To remove the files I<pict0000.jpg> .. I<pict9999.jpg> you could do:

B<seq -f %04g 0 9999 | parallel rm pict{}.jpg>

You could also do:

B<seq -f %04g 0 9999 | perl -pe 's/(.*)/pict$1.jpg/' | parallel -m rm>

The first will run B<rm> 10000 times, while the last will only run
B<rm> as many times needed to keep the command line length short
enough to avoid B<Argument list too long> (it typically runs 1-2 times).

You could also run:

B<seq -f %04g 0 9999 | parallel -X rm pict{}.jpg>

This will also only run B<rm> as many times needed to keep the command
line length short enough.


=head1 EXAMPLE: Compute intensive jobs and substitution

If ImageMagick is installed this will generate a thumbnail of a jpg
file:

B<convert -geometry 120 foo.jpg thumb_foo.jpg>

If the system has more than 1 CPU core it can be run with
number-of-cpu-cores jobs in parallel (B<-j> +0). This will do that for
all jpg files in a directory:

B<ls *.jpg | parallel -j +0 convert -geometry 120 {} thumb_{}>

To do it recursively use B<find>:

B<find . -name '*.jpg' | parallel -j +0 convert -geometry 120 {} {}_thumb.jpg>

Notice how the argument has to start with B<{}> as B<{}> will include path
(e.g. running B<convert -geometry 120 ./foo/bar.jpg
thumb_./foo/bar.jpg> would clearly be wrong). The command will
generate files like ./foo/bar.jpg_thumb.jpg.

Use B<{.}> to avoid the extra .jpg in the file name. This command will
make files like ./foo/bar_thumb.jpg:

B<find . -name '*.jpg' | parallel -j +0 convert -geometry 120 {} {.}_thumb.jpg>


=head1 EXAMPLE: Substitution and redirection

This will generate an uncompressed version of .gz-files next to the .gz-file:

B<ls *.gz | parallel zcat {} ">>B<"{.}>

Quoting of > is necessary to postpone the redirection. Another
solution is to quote the whole command:

B<ls *.gz | parallel "zcat {} >>B<{.}">

Other special shell charaters (such as * ; $ > < | >> <<) also needs
to be put in quotes, as they may otherwise be interpreted by the shell
and not given to GNU B<parallel>.

=head1 EXAMPLE: Composed commands

A job can consist of several commands. This will print the number of
files in each directory:

B<ls | parallel 'echo -n {}" "; ls {}|wc -l'>

To put the output in a file called <name>.dir:

B<ls | parallel '(echo -n {}" "; ls {}|wc -l) >> B<{}.dir'>


=head1 EXAMPLE: Removing file extension when processing files

When processing files removing the file extension using B<{.}> is
often useful.

Create a directory for each zip-file and unzip it in that dir:

B<ls *zip | parallel 'mkdir {.}; cd {.}; unzip ../{}'>

Recompress all .gz files in current directory using B<bzip2> running 1
job per CPU core in parallel:

B<ls *.gz | parallel -j+0 "zcat {} | bzip2 >>B<{.}.bz2 && rm {}">


=head1 EXAMPLE: Removing two file extensions when processing files and
calling GNU Parallel from itself

If you have directory with tar.gz files and want these extracted in
the corresponding dir (e.g foo.tar.gz will be extracted in the dir
foo) you can do:

B<ls *.tar.gz| parallel -U /// 'echo ///|parallel "mkdir -p {.} ; tar -C {.} -xf {.}.tar.gz"'>


=head1 EXAMPLE: Rewriting a for-loop and a while-loop

for-loops like this:

  (for x in `cat list` ; do
    do_something $x
  done) | process_output

and while-loops like this:

  cat list | (while read x ; do
    do_something $x
  done) | process_output

can be written like this:

B<cat list | parallel do_something | process_output>

If the processing requires more steps the for-loop like this:

 (for x in `cat list` ; do
   no_extension=${x%.png};
   do_something $x scale $no_extension.jpg
   do_step2 <$x $no_extension
 done) | process_output

and while-loops like this:

 cat list | (while read x ; do
   no_extension=${x%.png};
   do_something $x scale $no_extension.jpg
   do_step2 <$x $no_extension
 done) | process_output

can be written like this:

B<cat list | parallel "do_something {} scale {.}.jpg ; do_step2 <{} {.}" | process_output>


=head1 EXAMPLE: Group output lines

When runnning jobs that output data, you often do not want the output
of multiple jobs to run together. GNU B<parallel> defaults to grouping the
output of each job, so the output is printed when the job finishes. If
you want the output to be printed while the job is running you can use
B<-u>.

Compare the output of:

B<(echo foss.org.my; echo debian.org; echo freenetproject.org) | parallel traceroute>

to the output of:

B<(echo foss.org.my; echo debian.org; echo freenetproject.org) | parallel -u traceroute>


=head1 EXAMPLE: Keep order of output same as order of input

Normally the output of a job will be printed as soon as it
completes. Sometimes you want the order of the output to remain the
same as the order of the input. This is often important, if the output
is used as input for another system. B<-k> will make sure the order of
output will be in the same order as input even if later jobs end
before earlier jobs.

Append a string to every line in a text file:

B<cat textfile | parallel -k echo {} append_string>

If you remove B<-k> some of the lines may come out in the wrong order.

Another example is B<traceroute>:

B<(echo foss.org.my; echo debian.org; echo freenetproject.org) | parallel traceroute>

will give traceroute of foss.org.my, debian.org and
freenetproject.org, but it will be sorted according to which job
completed first.

To keep the order the same as input run:

B<(echo foss.org.my; echo debian.org; echo freenetproject.org) | parallel -k traceroute>

This will make sure the traceroute to foss.org.my will be printed
first.


=head1 EXAMPLE: Parallel grep

B<grep -r> greps recursively through directories. On multicore CPUs
GNU B<parallel> can often speed this up.

find . -type f | parallel -k -j150% -n 1000 -m grep -H -n STRING {}

This will run 1.5 job per core, and give 1000 arguments to B<grep>.


=head1 EXAMPLE: Using remote computers

To run commands on a remote computer SSH needs to be set up and you
must be able to login without entering a password (B<ssh-agent> may be
handy).

To run B<echo> on B<server.example.com>:

  seq 1 10 | parallel --sshlogin server.example.com echo

To run commands on more than one remote computer run:

  seq 1 10 | parallel --sshlogin server.example.com,server2.example.net echo

Or:

  seq 1 10 | parallel --sshlogin server.example.com \
    --sshlogin server2.example.net echo

If the login username is I<foo> on I<server2.example.net> use:

  seq 1 10 | parallel --sshlogin server.example.com \
    --sshlogin foo@server2.example.net echo

To distribute the commands to a list of computers, make a file
I<mycomputers> with all the computers:

  server.example.com
  foo@server2.example.com
  server3.example.com

Then run:

  seq 1 10 | parallel --sshloginfile mycomputers echo

To include the local computer add the special sshlogin ':' to the list:

  server.example.com
  foo@server2.example.com
  server3.example.com
  :

GNU B<parallel> will try to determine the number of CPU cores on each
of the remote computers, so B<-j+0> will run one job per CPU core -
even if the remote computers do not have the same number of CPU cores.

If the number of CPU cores on the remote servers is not identified
correctly the number of CPU cores can be added in front. Here the
server has 8 CPU cores.

  seq 1 10 | parallel --sshlogin 8/server.example.com echo


=head1 EXAMPLE: Transferring of files

To recompress gzipped files with B<bzip2> using a remote server run:

  find logs/ -name '*.gz' | \
    parallel --sshlogin server.example.com \
    --transfer "zcat {} | bzip2 -9 >{.}.bz2"

This will list the .gz-files in the I<logs> directory and all
directories below. Then it will transfer the files to
I<server.example.com> to the corresponding directory in
I<$HOME/logs>. On I<server.example.com> the file will be recompressed
using B<zcat> and B<bzip2> resulting in the corresponding file with
I<.gz> replaced with I<.bz2>.

If you want the resulting bz2-file to be transferred back to the local
computer add I<--return {.}.bz2>:

  find logs/ -name '*.gz' | \
    parallel --sshlogin server.example.com \
    --transfer --return {.}.bz2 "zcat {} | bzip2 -9 >{.}.bz2"

After the recompressing is done the I<.bz2>-file is transferred back to
the local computer and put next to the original I<.gz>-file.

If you want to delete the transferred files on the remote computer add
I<--cleanup>. This will remove both the file transferred to the remote
computer and the files transferred from the remote computer:

  find logs/ -name '*.gz' | \
    parallel --sshlogin server.example.com \
    --transfer --return {.}.bz2 --cleanup "zcat {} | bzip2 -9 >{.}.bz2"

If you want run on several servers add the servers to I<--sshlogin>
either using ',' or multiple I<--sshlogin>:

  find logs/ -name '*.gz' | \
    parallel --sshlogin server.example.com,server2.example.com \
    --sshlogin server3.example.com \
    --transfer --return {.}.bz2 --cleanup "zcat {} | bzip2 -9 >{.}.bz2"

You can add the local computer using I<--sshlogin :>. This will disable the
removing and transferring for the local computer only:

  find logs/ -name '*.gz' | \
    parallel --sshlogin server.example.com,server2.example.com \
    --sshlogin server3.example.com \
    --sshlogin : \
    --transfer --return {.}.bz2 --cleanup "zcat {} | bzip2 -9 >{.}.bz2"

Often I<--transfer>, I<--return> and I<--cleanup> are used together. They can be
shortened to I<--trc>:

  find logs/ -name '*.gz' | \
    parallel --sshlogin server.example.com,server2.example.com \
    --sshlogin server3.example.com \
    --sshlogin : \
    --trc {.}.bz2 "zcat {} | bzip2 -9 >{.}.bz2"

With the file I<mycomputers> containing the list of computers it becomes:

  find logs/ -name '*.gz' | parallel --sshloginfile mycomputers \
    --trc {.}.bz2 "zcat {} | bzip2 -9 >{.}.bz2"


=head1 EXAMPLE: Working as cat | sh. Ressource inexpensive jobs and evaluation

GNU B<parallel> can work similar to B<cat | sh>.

A ressource inexpensive job is a job that takes very little CPU, disk
I/O and network I/O. Ping is an example of a ressource inexpensive
job. wget is too - if the webpages are small.

The content of the file jobs_to_run:

  ping -c 1 10.0.0.1
  wget http://status-server/status.cgi?ip=10.0.0.1
  ping -c 1 10.0.0.2
  wget http://status-server/status.cgi?ip=10.0.0.2
  ...
  ping -c 1 10.0.0.255
  wget http://status-server/status.cgi?ip=10.0.0.255

To run 100 processes simultaneously do:

B<parallel -j 100 < jobs_to_run>

As there is not a I<command> the option B<-c> is default because the
jobs needs to be evaluated by the shell.


=head1 QUOTING

For more advanced use quoting may be an issue. The following will
print the filename for each line that has exactly 2 columns:

B<perl -ne '/^\S+\s+\S+$/ and print $ARGV,"\n"' file>

This can be done by GNU B<parallel> using:

B<ls | parallel "perl -ne '/^\\S+\\s+\\S+$/ and print \$ARGV,\"\\n\"'">

Notice how \'s, "'s, and $'s needs to be quoted. GNU B<parallel> can do
the quoting by using option B<-q>:

B<ls | parallel -q  perl -ne '/^\S+\s+\S+$/ and print $ARGV,"\n"'>

However, this means you cannot make the shell interpret special
characters. For example this B<will not work>:

B<ls *.gz | parallel -q "zcat {} >>B<{.}">

B<ls *.gz | parallel -q "zcat {} | bzip2 >>B<{.}.bz2">

because > and | need to be interpreted by the shell.

If you get errors like:

B<sh: -c: line 0: syntax error near unexpected token>

then you might try using B<-q>.

If you are using B<bash> process substitution like B<<(cat foo)> then
you may try B<-q> and prepending I<command> with B<bash -c>:

B<ls | parallel -q bash -c 'wc -c <(echo {})'>

Or for substituting output:

B<ls | parallel -q bash -c 'tar c {} | tee >>B<(gzip >>B<{}.tar.gz) | bzip2 >>B<{}.tar.bz2'>

B<Conclusion>: To avoid dealing with the quoting problems it may be
easier just to write a small script and have GNU B<parallel> call that
script.


=head1 LIST RUNNING JOBS

If you want a list of the jobs currently running you can run:

B<killall -USR1 parallel>

GNU B<parallel> will then print the currently running jobs on STDERR.


=head1 COMPLETE RUNNING JOBS BUT DO NOT START NEW JOBS

If you regret starting a lot of jobs you can simply break GNU B<parallel>,
but if you want to make sure you do not have halfcompleted jobs you
should send the signal B<SIGTERM> to GNU B<parallel>:

B<killall -TERM parallel>

This will tell GNU B<parallel> to not start any new jobs, but wait until
the currently running jobs are finished before exiting.


=head1 ENVIRONMENT VARIABLES

=over 9

=item $PARALLEL_PID - unimplemented

The environment variable $PARALLEL_PID is set by GNU B<parallel> and
is visible to the jobs started from GNU B<parallel>. This makes it
possible for the jobs to communicate directly to GNU <parallel>.

B<Example:> If each of the jobs tests a solution and one of jobs finds
the solution the job can tell GNU B<parallel> not to start more jobs
by: B<kill -TERM $PARALLEL_PID>. This only works on the local
computer.

=item $PARALLEL

The environment variable $PARALLEL will be used as default options for
GNU B<parallel>. However, because some options take arguments the
options need to be split into groups in which only the last option
takes an argument. Each group of options should be put on a line of its
own.

B<Example:>

B<cat list | parallel -j1 -k -v ls>

can be written as:

B<cat list | PARALLEL="-kvj1" parallel ls>

B<cat list | parallel -j1 -k -v -S"myssh user@server" ls>

can be written as:

B<cat list | PARALLEL="-kvj1>

B<-Smyssh user@server" parallel echo>

Notice the newline in the middle is needed because both B<-S> and
B<-j> take an argument and thus both need to be at the end of a group.

=back

=head1 INIT FILE (RC FILE)

The file ~/.parallelrc will be read if it exists. It should be
formatted like the environment variable $PARALLEL. Lines starting with
'#' will be ignored.


=head1 EXIT STATUS

If B<--halt-on-error> 0 or not specified:

=over 6

=item 0

All jobs ran without error.

=item 1-253

Some of the jobs failed. The exit status gives the number of failed jobs

=item 254

More than 253 jobs failed.

=item 255

Other error.

=back

If B<--halt-on-error> 1 or 2: Exit status of the failing job.


=head1 DIFFERENCES BETWEEN GNU Parallel AND ALTERNATIVES

There are a lot programs with some of the functionality of GNU
B<parallel>. GNU B<parallel> strives to include the best of the
functionality without sacrifying ease of use.


=head2 DIFFERENCES BETWEEN xargs AND GNU Parallel

B<xargs> offer some of the same possibilites as GNU B<parallel>.

B<xargs> deals badly with special characters (such as space, ' and
"). To see the problem try this:

  touch important_file
  touch 'not important_file'
  ls not* | xargs rm
  mkdir -p '12" records'
  ls | xargs rmdir

You can specify B<-0> or B<-d "\n">, but many input generators are not
optimized for using B<NUL> as separator but are optimized for
B<newline> as separator. E.g B<head>, B<tail>, B<awk>, B<ls>, B<echo>,
B<sed>, B<tar -v>, B<perl> (B<-0> and \0 instead of \n), B<locate>
(requires using B<-0>), B<find> (requires using B<-print0>), B<grep>
(requires user to use B<-z> or B<-Z>).

So GNU B<parallel>'s newline separation can be emulated with:

B<cat | xargs -d "\n" -n1 I<command>>

B<xargs> can run a given number of jobs in parallel, but has no
support for running number-of-cpu-cores jobs in parallel.

B<xargs> has no support for grouping the output, therefore output may
run together, e.g. the first half of a line is from one process and
the last half of the line is from another process. The example
B<Parallel grep> cannot be done reliably with B<xargs> because of
this.

B<xargs> has no support for keeping the order of the output, therefore
if running jobs in parallel using B<xargs> the output of the second
job cannot be postponed till the first job is done.

B<xargs> has no support for running jobs on remote computers.

B<xargs> has no support for context replace, so you will have to create the
arguments.

If you use a replace string in B<xargs> (B<-I>) you can not force
B<xargs> to use more than one argument.

Quoting in B<xargs> works like B<-q> in GNU B<parallel>. This means
composed commands and redirection require using B<bash -c>.

B<ls | parallel "wc {} >> B<{}.wc">

becomes

B<ls | xargs -d "\n" -P9 -I {} bash -c "wc {} >>B< {}.wc">

and

B<ls | parallel "echo {}; ls {}|wc">

becomes

B<ls | xargs -d "\n" -P9 -I {} bash -c "echo {}; ls {}|wc">


=head2 DIFFERENCES BETWEEN find -exec AND GNU Parallel

B<find -exec> offer some of the same possibilites as GNU B<parallel>.

B<find -exec> only works on files. So processing other input (such as
hosts or URLs) will require creating these inputs as files. B<find
-exec> has no support for running commands in parallel.


=head2 DIFFERENCES BETWEEN make -j AND GNU Parallel

B<make -j> can run jobs in parallel, but requires a crafted Makefile
to do this. That results in extra quoting to get filename containing
newline to work correctly.

B<make -j> has no support for grouping the output, therefore output
may run together, e.g. the first half of a line is from one process
and the last half of the line is from another process. The example
B<Parallel grep> cannot be done reliably with B<make -j> because of
this.

(Very early versions of GNU Parallel was coincidently implemented
using B<make -j>).


=head2 DIFFERENCES BETWEEN ppss AND GNU Parallel

B<ppss> is also a tool for running jobs in parallel.

The output of B<ppss> is status information and thus not useful for
using as input for another command. The output from the jobs are put
into files.

The argument replace string ($ITEM) cannot be changed. Arguments must
be quoted - thus arguments containing special characters (space '"&!*)
may cause problems. More than one argument is not supported. File
names containing newlines are not processed correctly. When reading
input from a file null cannot be used terminator. B<ppss> needs to
read the whole input file before starting any jobs.

Output and status information is stored in ppss_dir and thus requires
cleanup when completed. If the dir is not removed before running
B<ppss> again it may cause nothing to happen as B<ppss> thinks the
task is already done. GNU B<parallel> will normally not need cleaning
up if running locally and will only need cleaning up if stopped
abnormally and running remote (B<--cleanup> may not complete if
stopped abnormally). The example B<Parallel grep> would require extra
postprocessing if written using B<ppss>.

For remote systems PPSS requires 3 steps: config, deploy, and
start. GNU B<parallel> only requires one step.

=head3 EXAMPLES FROM ppss MANUAL

Here are the examples from B<ppss>'s manual page with the equivalent
using GNU B<parallel>:

./ppss.sh standalone -d /path/to/files -c 'gzip '

find /path/to/files -type f | parallel -j+0 gzip

./ppss.sh standalone -d /path/to/files -c 'cp "$ITEM" /destination/dir '

find /path/to/files -type f | parallel -j+0 cp {} /destination/dir

./ppss.sh standalone -f list-of-urls.txt -c 'wget -q '

parallel -a list-of-urls.txt wget -q

./ppss.sh standalone -f list-of-urls.txt -c 'wget -q "$ITEM"'

parallel -a list-of-urls.txt wget -q {}

./ppss config -C config.cfg -c 'encode.sh ' -d /source/dir -m 192.168.1.100 -u ppss -k ppss-key.key -S ./encode.sh -n nodes.txt -o /some/output/dir --upload --download

./ppss deploy -C config.cfg

./ppss start -C config

# parallel does not use configs. If you want a different username put it in nodes.txt: user@hostname

find source/dir -type f | parallel --sshloginfile nodes.txt --trc {.}.mp3 lame -a {} -o {.}.mp3 --preset standard --quiet

./ppss stop -C config.cfg

killall -TERM parallel

./ppss pause -C config.cfg

Press: CTRL-Z or killall -SIGTSTP parallel

./ppss continue -C config.cfg

Enter: fg or killall -SIGCONT parallel

./ppss.sh status -C config.cfg

killall -SIGUSR1 parallel # Not quite equivalent: Only shows the currently running jobs


=head2 DIFFERENCES BETWEEN pexec AND GNU Parallel

B<pexec> is also a tool for running jobs in parallel.

Here are the examples from B<pexec>'s info page with the equivalent
using parallel:

pexec -o sqrt-%s.dat -p "$(seq 10)" -e NUM -n 4 -c -- \
  'echo "scale=10000;sqrt($NUM)" | bc'

seq 10 | parallel -j4 'echo "scale=10000;sqrt({})" | bc > sqrt-{}.dat'

pexec -p "$(ls myfiles*.ext)" -i %s -o %s.sort -- sort

ls myfiles*.ext | parallel sort {} ">{}.sort"

pexec -f image.list -n auto -e B -u star.log -c -- \
  'fistar $B.fits -f 100 -F id,x,y,flux -o $B.star'

parallel -a image.list -j+0 \
  'fistar {}.fits -f 100 -F id,x,y,flux -o {}.star' 2>star.log

pexec -r *.png -e IMG -c -o - -- \
  'convert $IMG ${IMG%.png}.jpeg ; "echo $IMG: done"'

ls *.png | parallel 'convert {} {.}.jpeg; echo {}: done'

pexec -r *.png -i %s -o %s.jpg -c 'pngtopnm | pnmtojpeg'

ls *.png | parallel 'pngtopnm < {} | pnmtojpeg > {}.jpg'

for p in *.png ; do echo ${p%.png} ; done | \
  pexec -f - -i %s.png -o %s.jpg -c 'pngtopnm | pnmtojpeg'

ls *.png | parallel 'pngtopnm < {} | pnmtojpeg > {.}.jpg'

LIST=$(for p in *.png ; do echo ${p%.png} ; done)
  pexec -r $LIST -i %s.png -o %s.jpg -c 'pngtopnm | pnmtojpeg'

ls *.png | parallel 'pngtopnm < {} | pnmtojpeg > {.}.jpg'

pexec -n 8 -r *.jpg -y unix -e IMG -c \
  'pexec -j -m blockread -d $IMG | \
  jpegtopnm | pnmscale 0.5 | pnmtojpeg | \
  pexec -j -m blockwrite -s th_$IMG'

GNU B<parallel> does not support mutexes directly but uses B<mutex> to
do that.

ls *jpg | parallel -j8 'mutex -m blockread cat {} | jpegtopnm |' \
  'pnmscale 0.5 | pnmtojpeg | mutex -m blockwrite cat > th_{}'


=head2 DIFFERENCES BETWEEN xjobs AND GNU Parallel

B<xjobs> is also a tool for running jobs in parallel. It only supports
running jobs on your local computer.

B<xjobs> deals badly with special characters just like B<xargs>. See
the section B<DIFFERENCES BETWEEN xargs AND GNU Parallel>.

Here are the examples from B<xjobs>'s man page with the equivalent
using GNU B<parallel>:

ls -1 *.zip | xjobs unzip

ls *.zip | parallel unzip

ls -1 *.zip | xjobs -n unzip

ls *.zip | parallel unzip >/dev/null

find . -name '*.bak' | xjobs gzip

find . -name '*.bak' | parallel gzip

ls -1 *.jar | sed 's/\(.*\)/\1 > \1.idx/' | xjobs jar tf

ls *.jar | parallel jar tf {} '>' {}.idx

xjobs -s script

cat script | parallel

mkfifo /var/run/my_named_pipe;
xjobs -s /var/run/my_named_pipe &
echo unzip 1.zip >> /var/run/my_named_pipe;
echo tar cf /backup/myhome.tar /home/me >> /var/run/my_named_pipe

mkfifo /var/run/my_named_pipe;
cat /var/run/my_named_pipe | parallel &
echo unzip 1.zip >> /var/run/my_named_pipe;
echo tar cf /backup/myhome.tar /home/me >> /var/run/my_named_pipe


=head2 DIFFERENCES BETWEEN prll AND GNU parallel

B<prll> is also a tool for running jobs in parallel. It does not
support running jobs on remote computers.

B<prll> encourages using BASH aliases and BASH functions instead of
scripts. GNU B<parallel> will never support running aliases and
functions (see why http://www.perlmonks.org/index.pl?node_id=484296)
but scripts or composed commands work just fine.

B<prll> generates a lot of status information on STDERR which makes it
harder to use the STDERR output of the job directly as input for
another program.

Here is the example from B<prll>'s man page with the equivalent
using GNU B<parallel>:

prll -s 'mogrify -flip $1' *.jpg

ls *.jpg | parallel mogrify -flip


=head2 DIFFERENCES BETWEEN dxargs AND GNU Parallel

B<dxargs> is also a tool for running jobs in parallel.

B<dxargs> does not deal well with more simultaneous jobs than SSHD's
MaxStartup. B<dxargs> is only built for remote run jobs, but does not
support transferring of files.


=head2 DIFFERENCES BETWEEN mdm/middleman AND GNU Parallel

middleman(mdm) is also a tool for running jobs in parallel.

Here are the shellscripts of http://mdm.berlios.de/usage.html ported
to GNU B<parallel>:

B<seq 1 19 | parallel -j+0 buffon -o - | sort -n >>B< result>

B<cat files | parallel -j+0 cmd>


=head1 BUGS

Filenames beginning with '-' can cause some commands to give
unexpected results, as it will often be interpreted as an option.


=head1 REPORTING BUGS

Report bugs to <bug-parallel@gnu.org>.


=head1 AUTHOR

Copyright (C) 2007-10-18 Ole Tange, http://ole.tange.dk

Copyright (C) 2008,2009,2010 Ole Tange, http://ole.tange.dk

Copyright (C) 2010 Ole Tange, http://ole.tange.dk and Free Software
Foundation, Inc.

Parts of the manual concerning B<xargs> compatibility is inspired by
the manual of B<xargs> from GNU findutils 4.4.2.



=head1 LICENSE

Copyright (C) 2007,2008,2009,2010 Free Software Foundation, Inc.

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
at your option any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.

=head2 Documentation license I

Permission is granted to copy, distribute and/or modify this documentation
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with no
Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
Texts.  A copy of the license is included in the file fdl.txt.

=head2 Documentation license II

You are free:

=over 9

=item B<to Share>

to copy, distribute and transmit the work

=item B<to Remix>

to adapt the work

=back

Under the following conditions:

=over 9

=item B<Attribution>

You must attribute the work in the manner specified by the author or
licensor (but not in any way that suggests that they endorse you or
your use of the work).

=item B<Share Alike>

If you alter, transform, or build upon this work, you may distribute
the resulting work only under the same, similar or a compatible
license.

=back

With the understanding that:

=over 9

=item B<Waiver>

Any of the above conditions can be waived if you get permission from
the copyright holder.

=item B<Public Domain>

Where the work or any of its elements is in the public domain under
applicable law, that status is in no way affected by the license.

=item B<Other Rights>

In no way are any of the following rights affected by the license:

=over 2

=item *

Your fair dealing or fair use rights, or other applicable
copyright exceptions and limitations;

=item *

The author's moral rights;

=item *

Rights other persons may have either in the work itself or in
how the work is used, such as publicity or privacy rights.

=back

=back

=over 9

=item B<Notice>

For any reuse or distribution, you must make clear to others the
license terms of this work.

=back

A copy of the full license is included in the file as cc-by-sa.txt.

=head1 DEPENDENCIES

GNU B<parallel> uses Perl, and the Perl modules Getopt::Long, IPC::Open3,
Symbol, IO::File, POSIX, and File::Temp.


=head1 SEE ALSO

B<find>(1), B<xargs>(1), B<make>(1), B<pexec>(1), B<ppss>(1),
B<xjobs>(1), B<prll>(1), B<dxargs>(1), B<mdm>(1)

=cut


use IPC::Open3;
use Symbol qw(gensym);
use IO::File;
use POSIX ":sys_wait_h";
use File::Temp qw/ tempfile tempdir /;
use Getopt::Long;
use strict;

DoNotReap();
parse_options();
init_run_jobs();
start_more_jobs();
ReapIfNeeded();
drain_job_queue();
cleanup();
if($::opt_halt_on_error) {
    exit $Global::halt_on_error_exitstatus;
} else {
    exit(min($Global::exitstatus,254));
}

sub parse_options {
    # Defaults:
    $Global::version = 20100615;
    $Global::progname = 'parallel';
    $Global::debug = 0;
    $Global::verbose = 0;
    $Global::grouped = 1;
    $Global::keeporder = 0;
    $Global::quoting = 0;
    $Global::replacestring = '{}';
    $Global::replace_no_ext = '{.}';
    $/="\n";
    $Global::ignore_empty = 0;
    $Global::argfile = *STDIN;
    $Global::interactive = 0;
    $Global::stderr_verbose = 0;
    $Global::default_simultaneous_sshlogins = 9;
    $Global::exitstatus = 0;
    $Global::halt_on_error_exitstatus = 0;

    Getopt::Long::Configure ("bundling","require_order");
    # Add options from .parallelrc
    my $parallelrc = $ENV{'HOME'}."/.parallelrc";
    if(-r $parallelrc) {
	open (IN, "<", $parallelrc) || die;
	while(<IN>) {
	    /^\s*\#/ and next;
	    chomp;
	    unshift @ARGV, $_;
	}
	close IN;
    }
    # Add options from shell variable $PARALLEL
    $ENV{'PARALLEL'} and unshift @ARGV, split/\n/, $ENV{'PARALLEL'};
    GetOptions("debug|D" => \$::opt_D,
	       "xargs|m" => \$::opt_m,
	       "X" => \$::opt_X,
	       "v" => \$::opt_v,
	       "silent" => \$::opt_silent,
	       "keeporder|k" => \$::opt_k,
	       "group|g" => \$::opt_g,
	       "ungroup|u" => \$::opt_u,
	       "command|c" => \$::opt_c,
	       "file|f" => \$::opt_f,
	       "null|0" => \$::opt_0,
	       "quote|q" => \$::opt_q,
	       "I=s" => \$::opt_I,
	       "extensionreplace|U=s" => \$::opt_U,
	       "jobs|j=s" => \$::opt_P,
	       "max-line-length-allowed" => \$::opt_max_line_length_allowed,
	       "number-of-cpus" => \$::opt_number_of_cpus,
	       "number-of-cores" => \$::opt_number_of_cores,
	       "use-cpus-instead-of-cores" => \$::opt_use_cpus_instead_of_cores,
	       "sshlogin|S=s" => \@::opt_sshlogin,
	       "sshloginfile=s" => \$::opt_sshloginfile,
	       "controlmaster|M" => \$::opt_controlmaster,
	       "return=s" => \@::opt_return,
	       "trc=s" => \@::opt_trc,
	       "transfer" => \$::opt_transfer,
	       "cleanup" => \$::opt_cleanup,
	       "basefile|B=s" => \@::opt_basefile,
	       "halt-on-error|H=s" => \$::opt_halt_on_error,
	       "progress" => \$::opt_progress,
	       # xargs-compatibility - implemented, man, unittest
	       "max-procs|P=s" => \$::opt_P,
	       "delimiter|d=s" => \$::opt_d,
	       "max-chars|s=i" => \$::opt_s,
	       "arg-file|a=s" => \$::opt_a,
	       "no-run-if-empty|r" => \$::opt_r,
	       "replace|i:s" => \$::opt_i,
	       "E=s" => \$::opt_E,
	       "eof|e:s" => \$::opt_E,
	       "max-args|n=i" => \$::opt_n,
	       "help|h" => \$::opt_help,
	       "L=i" => \$::opt_L,
	       "max-lines|l:i" => \$::opt_l,
	       "verbose|t" => \$::opt_verbose,
	       "version|V" => \$::opt_version,
	       "show-limits" => \$::opt_show_limits,
	       "exit|x" => \$::opt_x,
	       ## xargs-compatibility - implemented, man - unittest missing
	       "interactive|p" => \$::opt_p,
	       ## How to unittest? tty must be emulated
	) || die_usage();
    $Global::debug = (defined $::opt_D);
    $Global::input_is_filename = (@ARGV);
    if(defined $::opt_m) { $Global::xargs = 1; }
    if(defined $::opt_X) { $Global::Xargs = 1; }
    if(defined $::opt_v) { $Global::verbose = 1; }
    if(defined $::opt_silent) { $Global::verbose = 0; }
    if(defined $::opt_k) { $Global::keeporder = 1; }
    if(defined $::opt_g) { $Global::grouped = 1; }
    if(defined $::opt_u) { $Global::grouped = 0; }
    if(defined $::opt_c) { $Global::input_is_filename = 0; }
    if(defined $::opt_f) { $Global::input_is_filename = 1; }
    if(defined $::opt_0) { $/ = "\0"; }
    if(defined $::opt_d) { my $e="sprintf \"$::opt_d\""; $/ = eval $e; }
    if(defined $::opt_p) { $Global::interactive = $::opt_p; }
    if(defined $::opt_q) { $Global::quoting = 1; }
    if(defined $::opt_r) { $Global::ignore_empty = 1; }
    if(defined $::opt_verbose) { $Global::stderr_verbose = 1; }
    if(defined $::opt_I) { $Global::replacestring = $::opt_I; }
    if(defined $::opt_U) { $Global::replace_no_ext = $::opt_U; }
    if(defined $::opt_i and $::opt_i) { $Global::replacestring = $::opt_i; }
    if(defined $::opt_E and $::opt_E) { $Global::end_of_file_string = $::opt_E; }
    if(defined $::opt_L and $::opt_L or defined $::opt_l) {
	$Global::max_lines = $::opt_l || $::opt_L || 1;
	$Global::max_number_of_args = $Global::max_lines;
    }
    if(defined $::opt_n and $::opt_n) { $Global::max_number_of_args = $::opt_n; }
    if(defined $::opt_help) { die_usage(); }
    if(defined $::opt_number_of_cpus) { print no_of_cpus(),"\n"; exit(0); }
    if(defined $::opt_number_of_cores) { print no_of_cores(),"\n"; exit(0); }
    if(defined $::opt_max_line_length_allowed) { print real_max_length(),"\n"; exit(0); }
    if(defined $::opt_version) { version(); exit(0); }
    if(defined $::opt_show_limits) { show_limits(); }
    if(defined @::opt_sshlogin) { @Global::sshlogin = @::opt_sshlogin; }
    if(defined $::opt_sshloginfile) { read_sshloginfile($::opt_sshloginfile); }
    if(defined @::opt_return) { push @Global::ret_files, @::opt_return; }
    if(defined @::opt_trc) {
	push @Global::ret_files, @::opt_trc;
	$::opt_transfer = 1;
	$::opt_cleanup = 1;
    }

    if(defined $::opt_a) {
	if(not open(ARGFILE,"<",$::opt_a)) {
	    print STDERR "$Global::progname: ".
		"Cannot open input file `$::opt_a': ".
		"No such file or directory\n";
	    exit(255);
	}
	$Global::argfile = *ARGFILE;
    }

    if(@ARGV) {
	if($Global::quoting) {
	    $Global::command = shell_quote(@ARGV);
	} else {
	    $Global::command = join(" ", @ARGV);
	}
    }

    parse_sshlogin();

    if(remote_hosts() and ($Global::xargs or $Global::Xargs)) {
	print STDERR ("Warning: using -X or -m with --sshlogin may fail\n");
    }

    # Needs to be done after setting $Global::command and $Global::command_line_max_len
    # as '-m' influences the number of commands that needs to be run
    if(defined $::opt_P) {
	for my $sshlogin (keys %Global::host) {
	    $Global::host{$sshlogin}{'max_no_of_running'} =
		compute_number_of_processes($::opt_P,$sshlogin);
	}
    } else {
	for my $sshlogin (keys %Global::host) {
	    $Global::host{$sshlogin}{'max_no_of_running'} =
		$Global::default_simultaneous_sshlogins;
	}
    }
    $Global::job_end_sequence=1;
}

sub cleanup {
    if(@::opt_basefile) {
	cleanup_basefile();
    }
}

#
# Generating the command line
#

sub no_extension {
    my $no_ext = shift;
    $no_ext =~ s:\.[^/\.]*$::; # Remove .ext from argument
    return $no_ext;
}

sub generate_command_line {
    my $command = shift;
    my ($job_line,$last_good);
    my ($next_arg,@quoted_args,@quoted_args_no_ext,$arg_length);
    my ($number_of_substitution,
	$number_of_substitution_no_ext,$spaces,
	$length_of_command_no_args,$length_of_context) =
	    xargs_computations($command);
    my $number_of_args = 0;
    while (defined($next_arg = get_next_arg())) {
	my $next_arg_no_ext = no_extension($next_arg);
	push (@quoted_args, $next_arg);
	push (@quoted_args_no_ext, $next_arg_no_ext);
	$number_of_args++;

	# Emulate xargs if there is a command and -x or -X is set
	my $next_arg_len =
	    $number_of_substitution * (length ($next_arg) + $spaces)
	    + $number_of_substitution_no_ext * (length ($next_arg_no_ext) + $spaces)
	    + $length_of_context;
	$arg_length += $next_arg_len;
	my $job_line_length = $length_of_command_no_args + $arg_length;
	if($job_line_length >= max_length_of_command_line()) {
	    unget_arg(pop @quoted_args);
	    if($::opt_x and $length_of_command_no_args + $next_arg_len
	       >= max_length_of_command_line()) {
		# To be compatible with xargs -x
		print STDERR ("Command line too long ($job_line_length >= "
			      . max_length_of_command_line() .
			      ") at number $number_of_args: ".
			      (substr($next_arg,0,50))."...\n");
		exit(255);
	    }
	    if(defined $quoted_args[0]) {
		last;
	    } else {
		print STDERR ("Command line too long ($job_line_length >= "
			      . max_length_of_command_line() .
			      ") at number $number_of_args: ".
			      (substr($next_arg,0,50))."...\n");
		exit(255);
	    }
	}
	if($Global::max_number_of_args and
	   $number_of_args >= $Global::max_number_of_args) {
	    last;
	}
	if(not $Global::xargs and not $Global::Xargs) {
	    # No xargs-mode: Just one argument per line
	    last;
	}
    }
    if(@quoted_args) {
	$job_line = $command;
	if(defined $job_line and
	   ($job_line =~/\Q$Global::replacestring\E/o or
	    $job_line =~/\Q$Global::replace_no_ext\E/o)) {
	    # substitute {} and {.} with args
	    if($Global::Xargs) {
		# Context sensitive replace (foo{}bar with fooargsbar)
		$job_line =
		    context_replace($job_line, \@quoted_args, \@quoted_args_no_ext);
	    } else {
		# Normal replace {} with args and {.} with args without extension
		my $arg=join(" ",@quoted_args);
		my $arg_no_ext=join(" ",@quoted_args_no_ext);
		$job_line =~ s/\Q$Global::replacestring\E/$arg/go;
		$job_line =~ s/\Q$Global::replace_no_ext\E/$arg_no_ext/go;
	    }
	} else {
	    # append args
	    my $arg=join(" ",@quoted_args);
	    if($job_line) {
		$job_line .= " ".$arg;
	    } else {
		# Parallel behaving like '|sh'
		$job_line = $arg;
	    }
	}
	debug("Return jobline: !$job_line!\n");
    }
    return ($job_line,\@quoted_args);
}


sub xargs_computations {
    my $command = shift;
    if(not @Calculated::xargs_computations) {
	my ($number_of_substitution, $number_of_substitution_no_ext,
	     $spaces,$length_of_command_no_args,$length_of_context)
	    = (1,0,0,0,0);
	if($command) {
	    # Count number of {}'s on the command line
	    my $no_of_replace =
		($command =~ s/\Q$Global::replacestring\E/$Global::replacestring/go);
	    $number_of_substitution = $no_of_replace || 1;
	    # Count number of {.}'s on the command line
	    my $no_of_no_ext =
		($command =~ s/\Q$Global::replace_no_ext\E/$Global::replace_no_ext/go);
	    $number_of_substitution_no_ext = $no_of_no_ext || 0;
	    # Count
	    my $c = $command;
	    if($Global::Xargs) {
		$c =~ s/\S*\Q$Global::replacestring\E\S*//go;
		$c =~ s/\S*\Q$Global::replace_no_ext\E\S*//go;
		$length_of_command_no_args = length($c) - 1;
		$length_of_context = length($command) - $length_of_command_no_args
		    - $no_of_replace * length($Global::replacestring)
		    - $no_of_no_ext * length($Global::replace_no_ext);
		$spaces = 0;
	    } else {
		# remove all {}s
		$c =~ s/\Q$Global::replacestring\E|\Q$Global::replace_no_ext\E//og;
		$length_of_command_no_args = length($c) -
		    $no_of_replace - $no_of_no_ext;
		$length_of_context = 0;
		$spaces = 1;
	    }
	}
	@Calculated::xargs_computations =
	    ($number_of_substitution, $number_of_substitution_no_ext,
	     $spaces,$length_of_command_no_args,$length_of_context);
    }
    return (@Calculated::xargs_computations);
}


sub shell_quote {
    # Quote the string so shell will not expand any special chars
    my (@strings) = (@_);
    my $arg;
    for $arg (@strings) {
	$arg =~ s/\\/\\\\/g;
	
	$arg =~ s/([\#\?\`\(\)\*\>\<\~\|\; \"\!\$\&\'])/\\$1/g;
	$arg =~ s/([\002-\011\013-\032])/\\$1/g;
	$arg =~ s/([\n])/'\n'/g; # filenames with '\n' is quoted using \'
    }
    return wantarray ? @strings : "@strings";
}


sub shell_unquote {
    # Unquote strings from shell_quote
    my (@strings) = (@_);
    my $arg;
    for $arg (@strings) {
	$arg =~ s/'\n'/\n/g; # filenames with '\n' is quoted using \'
	$arg =~ s/\\([\002-\011\013-\032])/$1/g;
	$arg =~ s/\\([\#\?\`\(\)\*\>\<\~\|\; \"\!\$\&\'])/$1/g;
	$arg =~ s/\\\\/\\/g;
    }
    return wantarray ? @strings : "@strings";
}


# Replace foo{}bar or foo{.}bar
sub context_replace {
    my ($job_line,$quoted,$no_ext) = (@_);
    while($job_line =~/\Q$Global::replacestring\E|\Q$Global::replace_no_ext\E/o) {
	$job_line =~ /(\S*(\Q$Global::replacestring\E|\Q$Global::replace_no_ext\E)\S*)/o
	    or die ("This should never happen");
	my $wordarg = $1; # This is the context that needs to be substituted
	my @all_word_arg;
	for my $n (0 .. $#$quoted) {
	    my $arg = $quoted->[$n];
	    my $arg_no_ext = $no_ext->[$n];
	    my $substituted = $wordarg;
	    $substituted=~s/\Q$Global::replacestring\E/$arg/go;
	    $substituted=~s/\Q$Global::replace_no_ext\E/$arg_no_ext/go;
	    push @all_word_arg, $substituted;
	}
	my $all_word_arg = join(" ",@all_word_arg);
	$job_line =~ s/\Q$wordarg\E/$all_word_arg/;
    }
    return $job_line;
}

#
# Number of processes, filehandles, max length of command line
#

# Maximal command line length (for -m and -X)
sub max_length_of_command_line {
    # Find the max_length of a command line
    # First find an upper bound
    if(not $Global::command_line_max_len) {
	$Global::command_line_max_len = real_max_length();
	if($::opt_s) {
	    if($::opt_s <= $Global::command_line_max_len) {
		$Global::command_line_max_len = $::opt_s;
	    } else {
		print STDERR "$Global::progname: ",
		"value for -s option should be < $Global::command_line_max_len\n";
	    }
	}
    }
    return $Global::command_line_max_len;
}

sub real_max_length {
    my $len = 10;
    do {
	$len *= 10;
    } while (is_acceptable_command_line_length($len));
    # Then search for the actual max length between 0 and upper bound
    return binary_find_max_length(int(($len)/10),$len);
}


sub binary_find_max_length {
    # Given a lower and upper bound find the max_length of a command line
    my ($lower, $upper) = (@_);
    if($lower == $upper or $lower == $upper-1) { return $lower; }
    my $middle = int (($upper-$lower)/2 + $lower);
    debug("Maxlen: $lower,$upper,$middle\n");
    if (is_acceptable_command_line_length($middle)) {
	return binary_find_max_length($middle,$upper);
    } else {
	return binary_find_max_length($lower,$middle);
    }
}

sub is_acceptable_command_line_length {
    # Test if a command line of this length can run
    my $len = shift;
    $Global::is_acceptable_command_line_length++;
    debug("$Global::is_acceptable_command_line_length $len\n");
    local *STDERR;
    open (STDERR,">/dev/null");
    system "true "."x"x$len;
    close STDERR;
    return not $?;
}

# Number of parallel processes to run

sub compute_number_of_processes {
    # Number of processes wanted and limited by system ressources
    my $opt_P = shift;
    my $sshlogin = shift;
    my $wanted_processes = user_requested_processes($opt_P,$sshlogin);
    debug("Wanted procs: $wanted_processes\n");
    my $system_limit =
	processes_available_by_system_limit($wanted_processes,$sshlogin);
    debug("Limited to procs: $system_limit\n");
    return $system_limit;
}

sub processes_available_by_system_limit {
    # If the wanted number of processes is bigger than the system limits:
    # Limit them to the system limits
    # Limits are: File handles, number of input lines, processes,
    # and taking > 1 second to spawn 10 extra processes

    my $wanted_processes = shift;
    my $sshlogin = shift;
    my $system_limit=0;
    my @command_lines=();
    my ($next_command_line, $args_ref);
    my $more_filehandles;
    my $max_system_proc_reached=0;
    my $spawning_too_slow=0;
    my $time = time;
    my %fh;
    my @children;
    DoNotReap();

    # Reserve filehandles
    # perl uses 7 filehandles for something?
    # parallel uses 1 for memory_usage
    for my $i (1..8) {
	open($fh{"init-$i"},"</dev/null");
    }
    do {
	$system_limit++;

	# If there are no more command lines, then we have a process
	# per command line, so no need to go further
	($next_command_line, $args_ref) = next_command_line();
	if(defined $next_command_line) {
	    push(@command_lines, $next_command_line, $args_ref);
	}

	# Every simultaneous process uses 2 filehandles when grouping
	$more_filehandles = open($fh{$system_limit*2},"</dev/null")
	    && open($fh{$system_limit*2+1},"</dev/null");

	# System process limit
	$system_limit % 10 or $time=time;
	my $child;
	if($child = fork()) {
	    push (@children,$child);
	} elsif(defined $child) {
	    # The child takes one process slot
	    # It will be killed later
	    sleep 100000;
	    exit(0);
	} else {
	    $max_system_proc_reached = 1;
	}
	debug("Time to fork ten procs ", time-$time, " process ", $system_limit);
	if(time-$time > 2) {
	    # It took more than 2 second to fork ten processes. We should stop forking.
	    # Let us give the system a little slack
	    debug("\nLimiting processes to: $system_limit-10%=".
		  (int ($system_limit * 0.9)+1)."\n");
	    $system_limit = int ($system_limit * 0.9)+1;
	    $spawning_too_slow = 1;
	}
    } while($system_limit < $wanted_processes
	    and defined $next_command_line
	    and $more_filehandles
	    and not $max_system_proc_reached
	    and not $spawning_too_slow);
    if($system_limit < $wanted_processes and not $more_filehandles) {
	print STDERR ("Warning: Only enough filehandles to run ",
		      $system_limit, " jobs in parallel. ",
		      "Raising ulimit -n may help\n");
    }
    if($system_limit < $wanted_processes and $max_system_proc_reached) {
	print STDERR ("Warning: Only enough available processes to run ",
		      $system_limit, " jobs in parallel.\n");
    }
    if($system_limit < $wanted_processes and $spawning_too_slow) {
	print STDERR ("Warning: Starting 10 extra processes takes > 2 sec.\n",
		      "Limiting to ", $system_limit, " jobs in parallel.\n");
    }
    # Cleanup: Close the files
    for (values %fh) { close $_ }
    # Cleanup: Kill the children
    for my $pid (@children) {
	kill 15, $pid;
	waitpid($pid,0);
    }
    wait();
    # Cleanup: Unget the command_lines (and args_refs)
    unget_command_line(@command_lines);
    if($sshlogin ne ":" and
       $system_limit > $Global::default_simultaneous_sshlogins) {
	$system_limit =
	    simultaneous_sshlogin_limit($sshlogin,$system_limit);
    }
    return $system_limit;
}

sub simultaneous_sshlogin {
    # Using $sshlogin try to see if we can do $wanted_processes
    # simultaneous logins
    my $sshlogin = shift;
    my $wanted_processes = shift;
    my ($sshcmd,$serverlogin) = sshcommand_of_sshlogin($sshlogin);
    my $cmd = "$sshcmd $serverlogin echo simultaneouslogin 2>&1 &"x$wanted_processes;
    debug("Trying $wanted_processes logins at $serverlogin");
    open (SIMUL, "($cmd)|grep simultaneouslogin | wc -l|") or die;
    my $ssh_limit = <SIMUL>;
    close SIMUL;
    chomp $ssh_limit;
    return $ssh_limit;
}

sub simultaneous_sshlogin_limit {
    # Test by logging in wanted number of times simultaneously
    # (ssh e echo simultaneouslogin &ssh e echo simultaneouslogin &...)|grep simul|wc -l
    # Return min($wanted_processes,$working_simultaneous_ssh_logins-1)
    my $sshlogin = shift;
    my $wanted_processes = shift;
    my ($sshcmd,$serverlogin) = sshcommand_of_sshlogin($sshlogin);
    # Try twice because it guesses wrong sometimes
    # Choose the minimal
    my $ssh_limit =
	min(simultaneous_sshlogin($sshlogin,$wanted_processes),
	    simultaneous_sshlogin($sshlogin,$wanted_processes));
    if($ssh_limit < $wanted_processes) {
	print STDERR
	    ("Warning: ssh to $serverlogin only allows ",
	     "for $ssh_limit simultaneous logins.\n",
	     "You may raise this by changing ",
	     "/etc/ssh/sshd_config:MaxStartup on $serverlogin\n",
	     "Using only ",$ssh_limit-1," connections ",
	     "to avoid race conditions\n");
    }
    # Race condition can cause problem if using all sshs.
    if($ssh_limit > 1) { $ssh_limit -= 1; }
    return $ssh_limit;
}

sub enough_file_handles {
    # check that we have enough filehandles available for starting
    # another job
    if($Global::grouped) {
	my %fh;
	my $enough_filehandles = 1;
	# We need a filehandle for STDOUT and STDERR
	# open3 uses 2 extra filehandles temporarily
	for my $i (1..4) {
	    $enough_filehandles &&= open($fh{$i},"</dev/null");
	}
	for (values %fh) { close $_; }
	return $enough_filehandles;
    } else {
	return 1;
    }
}

sub user_requested_processes {
    # Parse the number of processes that the user asked for
    my $opt_P = shift;
    my $sshlogin = shift;
    my $processes;
    if(defined $opt_P) {
	if($opt_P =~ /^\+(\d+)$/) {
	    # E.g. -P +2
	    my $j = $1;
	    $processes =
		$j + no_of_processing_units_sshlogin($sshlogin);
	} elsif ($opt_P =~ /^-(\d+)$/) {
	    # E.g. -P -2
	    my $j = $1;
	    $processes =
		no_of_processing_units_sshlogin($sshlogin) - $j;
	} elsif ($opt_P =~ /^(\d+)\%$/) {
	    my $j = $1;
	    $processes =
		no_of_processing_units_sshlogin($sshlogin) * $j / 100;
	} elsif ($opt_P =~ /^(\d+)$/) {
	    $processes = $1;
	    if($processes == 0) {
		# -P 0 = infinity (or at least close)
		$processes = 2**31;
	    }
	} else {
	    die_usage();
	}
	if($processes < 1) {
	    $processes = 1;
	}
    }
    return $processes;
}

sub no_of_processing_units_sshlogin {
    # Number of processing units (CPUs or cores) at this sshlogin
    my $sshlogin = shift;
    my ($sshcmd,$serverlogin) = sshcommand_of_sshlogin($sshlogin);
    if(not $Global::host{$sshlogin}{'ncpus'}) {
	if($serverlogin eq ":") {
	    if($::opt_use_cpus_instead_of_cores) {
		$Global::host{$sshlogin}{'ncpus'} = no_of_cpus();
	    } else {
		$Global::host{$sshlogin}{'ncpus'} = no_of_cores();
	    }
	} else {
	    my $ncpu;
	    if($::opt_use_cpus_instead_of_cores) {
		$ncpu = qx(echo|$sshcmd $serverlogin parallel --number-of-cpus);
		chomp($ncpu);
	    } else {
		$ncpu = qx(echo|$sshcmd $serverlogin parallel --number-of-cores);
		chomp($ncpu);
	    }
	    if($ncpu =~ /^[0-9]+$/) {
		$Global::host{$sshlogin}{'ncpus'} = $ncpu;
	    } else {
		print STDERR ("Warning: Could not figure out ",
			      "number of cpus on $serverlogin. Using 1");
		$Global::host{$sshlogin}{'ncpus'} = 1;
	    }
	}
    }
    return $Global::host{$sshlogin}{'ncpus'};
}

sub no_of_cpus {
    if(not $Global::no_of_cpus) {
	local $/="\n"; # If delimiter is set, then $/ will be wrong
	my $no_of_cpus = (no_of_cpus_freebsd()
			  || no_of_cpus_darwin()
			  || no_of_cpus_solaris()
			  || no_of_cpus_gnu_linux()
	    );
	if($no_of_cpus) {
	    $Global::no_of_cpus = $no_of_cpus;
	} else {
	    warn("Cannot figure out number of cpus. Using 1");
	    $Global::no_of_cpus = 1;
	}
    }
    return $Global::no_of_cpus;
}

sub no_of_cores {
    if(not $Global::no_of_cores) {
	local $/="\n"; # If delimiter is set, then $/ will be wrong
	my $no_of_cores = (no_of_cores_freebsd()
			   || no_of_cores_darwin()
			   || no_of_cores_solaris()
			   || no_of_cores_gnu_linux()
	    );
	if($no_of_cores) {
	    $Global::no_of_cores = $no_of_cores;
	} else {
	    warn("Cannot figure out number of CPU cores. Using 1");
	    $Global::no_of_cores = 1;
	}
    }
    return $Global::no_of_cores;
}

sub no_of_cpus_gnu_linux {
    my $no_of_cpus;
    if(-e "/proc/cpuinfo") {
	$no_of_cpus = 0;
	my %seen;
	open(IN,"cat /proc/cpuinfo|") || return undef;
	while(<IN>) {
	    if(/^physical id.*[:](.*)/ and not $seen{$1}++) {
		$no_of_cpus++;
	    }
	}
	close IN;
    }
    return $no_of_cpus;
}

sub no_of_cores_gnu_linux {
    my $no_of_cores;
    if(-e "/proc/cpuinfo") {
	$no_of_cores = 0;
	open(IN,"cat /proc/cpuinfo|") || return undef;
	while(<IN>) {
	    /^processor.*[:]/ and $no_of_cores++;
	}
	close IN;
    }
    return $no_of_cores;
}

sub no_of_cpus_darwin {
    my $no_of_cpus = `sysctl -a hw 2>/dev/null | grep -w physicalcpu | awk '{ print \$2 }'`;
    return $no_of_cpus;
}

sub no_of_cores_darwin {
    my $no_of_cores = `sysctl -a hw  2>/dev/null | grep -w logicalcpu | awk '{ print \$2 }'`;
    return $no_of_cores;
}

sub no_of_cpus_freebsd {
    my $no_of_cpus = `sysctl hw.ncpu 2>/dev/null | awk '{ print \$2 }'`;
    return $no_of_cpus;
}

sub no_of_cores_freebsd {
    my $no_of_cores = `sysctl -a hw  2>/dev/null | grep -w logicalcpu | awk '{ print \$2 }'`;
    return $no_of_cores;
}

sub no_of_cpus_solaris {
    if(-x "/usr/sbin/psrinfo") {
	my @psrinfo = `/usr/sbin/psrinfo`;
	if($#psrinfo >= 0) {
	    return $#psrinfo +1;
	}
    }
    if(-x "/usr/sbin/prtconf") {
	my @prtconf = `/usr/sbin/prtconf | grep cpu..instance`;
	if($#prtconf >= 0) {
	    return $#prtconf +1;
	}
    }
    return undef;
}

sub no_of_cores_solaris {
    if(-x "/usr/sbin/psrinfo") {
	my @psrinfo = `/usr/sbin/psrinfo`;
	if($#psrinfo >= 0) {
	    return $#psrinfo +1;
	}
    }
    if(-x "/usr/sbin/prtconf") {
	my @prtconf = `/usr/sbin/prtconf | grep cpu..instance`;
	if($#prtconf >= 0) {
	    return $#prtconf +1;
	}
    }
    return undef;
}

#
# General useful library functions
#

sub min {
    my $min = shift;
    my @args = @_;
    for my $a (@args) {
	$min = ($min < $a) ? $min : $a;
    }
    return $min;
}


#
# Running and printing the jobs
#

# Variable structure:
#    $Global::running{$pid}{'seq'} = printsequence
#    $Global::running{$pid}{sshlogin} = server to run on
#    $Global::running{$pid}{'exitstatus'} = exit status
#    $Global::host{$sshlogin}{'no_of_running'} = number of currently running jobs
#    $Global::host{$sshlogin}{'completed'} = number of completed jobs
#    $Global::host{$sshlogin}{'ncpus'} = number of CPUs (or CPU cores)
#    $Global::host{$sshlogin}{'maxlength'} = max line length (currently buggy for remote)
#    $Global::host{$sshlogin}{'max_no_of_running'} = max parallel running jobs
#    $Global::host{$sshlogin}{'sshcmd'} = command to use as ssh
#    $Global::host{$sshlogin}{'serverlogin'} = username@hostname
#    $Global::total_running = total number of running jobs
#    $Global::total_started = total jobs started
#    $Global::total_jobs = total jobs to be started at all
#    $Global::total_completed = total jobs completed

sub init_run_jobs {
    # Remember the original STDOUT and STDERR
    open $Global::original_stdout, ">&STDOUT" or die "Can't dup STDOUT: $!";
    open $Global::original_stderr, ">&STDERR" or die "Can't dup STDERR: $!";
    open $Global::original_stdin, "<&STDIN" or die "Can't dup STDIN: $!";
    $Global::total_running = 0;
    $Global::total_started = 0;
    $Global::total_completed = 0;
    $SIG{USR1} = \&ListRunningJobs;
    $SIG{USR2} = \&toggle_progress;
    $Global::original_sigterm = $SIG{TERM};
    $SIG{TERM} = \&StartNoNewJobs;
    if(@::opt_basefile) {
	setup_basefile();
    }
}

sub login_and_host {
    my $sshlogin = shift;
    $sshlogin =~ /(\S+$)/ or die;
    return $1;
}

sub next_command_line_with_sshlogin {
    my $sshlogin = shift;
    my ($next_command_line, $args_ref) = next_command_line();
    my ($sshcmd,$serverlogin) = sshcommand_of_sshlogin($sshlogin);
    my ($pre,$post)=("","");
    if($next_command_line and $serverlogin ne ":") {
	for my $file (@$args_ref) {
	    if($::opt_transfer) {
		# --transfer
		$pre .= sshtransfer($sshlogin,$file).";";
	    }
	    if(@Global::ret_files) {
		# --return or --trc
		$post .= sshreturn($sshlogin,$file).";";
	    }
	    if($::opt_cleanup) {
		# --cleanup
		$post .= sshcleanup($sshlogin,$file).";";
	    }
	}
	if($post) {
	    # We need to save the exit status of the job
	    $post = '_EXIT_status=$?; '.$post.' exit $_EXIT_status;';
	}
	return ($pre . "$sshcmd $serverlogin "
		.shell_quote($next_command_line).";".$post);
    } else {
	return $next_command_line;
    }
}

sub next_command_line {
    my ($cmd_line,$args_ref);
    if(@Global::unget_next_command_line) {
	$cmd_line = shift @Global::unget_next_command_line;
	$args_ref = shift @Global::unget_next_command_line;
    } else {
	do {
	    ($cmd_line,$args_ref) = generate_command_line($Global::command);
	} while (defined $cmd_line and $cmd_line =~ /^\s*$/); # Skip empty lines
    }
    return ($cmd_line,$args_ref);
}

sub unget_command_line {
    push @Global::unget_next_command_line, @_;
}

sub get_next_arg {
    my $arg;
    if(@Global::unget_arg) {
	$arg = shift @Global::unget_arg;
    } else {
	if(eof $Global::argfile) {
	    return undef;
	}
	$arg = <$Global::argfile>;
	chomp $arg;
	if($Global::end_of_file_string and
	   $arg eq $Global::end_of_file_string) {
	    # Ignore the rest of STDIN
	    while (<$Global::argfile>) {}
	    return undef;
	}
	if($Global::ignore_empty) {
	    if($arg =~ /^\s*$/) {
		return get_next_arg();
	    }
	}
	if($Global::max_lines) {
	    if($arg =~ /\s$/) {
		# Trailing space => continued on next line
		$arg .= get_next_arg();
	    }
	}
	if($Global::input_is_filename) {
	    $arg = shell_quote($arg);
	}
    }
    debug("Next arg: !".$arg."!\n");
    return $arg;
}

sub unget_arg {
    push @Global::unget_arg, @_;
}

sub drain_job_queue {
    if($::opt_progress) {
	print init_progress();
    }
    my $last_header="";
    while($Global::total_running > 0) {
	debug("jobs running: $Global::total_running Memory usage:".my_memory_usage()."\n");
	sleep 1;
	if($::opt_progress) {
	    my %progress = progress();
	    if($last_header ne $progress{'header'}) {
		print "\n",$progress{'header'},"\n";
		$last_header = $progress{'header'};
	    }
	    print "\r",$progress{'status'};
	}
    }
    if($::opt_progress) {
	print "\n";
    }
}

sub toggle_progress {
    # Turn on/off progress view
    $::opt_progress = not $::opt_progress;
    if($::opt_progress) {
	print init_progress();
    }
}

sub init_progress {
    $|=1;
    my %progress = progress();
    return ("\nComputers / CPU cores / Max jobs to run\n",
	    $progress{'workerlist'},"\n");
}

sub progress {
    my $termcols = columns();
    my ($status, $header)=("x"x($termcols+1),"");
    my @workers = sort keys %Global::host;
    my %sshlogin = map { $_ eq ":" ? ($_=>"local") : ($_=>$_) } @workers;
    my $workerno = 1;
    my %workerno = map { ($_=>$workerno++) } @workers;
    my $workerlist = join("\n", map {
	$workerno{$_}.":".$sshlogin{$_} ." / ".
	    ($Global::host{$_}{'ncpus'} || "-") ." / ".
	    $Global::host{$_}{'max_no_of_running'}
			  } @workers);
    if(eof $Global::argfile) {
	# sshlogin1:XX/XX/XX% sshlogin2:XX/XX/XX% sshlogin3:XX/XX/XX%
	$header = "Computer:jobs running/jobs completed/%completed of all jobs";
	$status = join(" ",map
		       { sprintf("%s:%d/%d/%d%%",
				 $sshlogin{$_}, $Global::host{$_}{'no_of_running'},
				 ($Global::host{$_}{'completed'}||0),
				 ($Global::host{$_}{'completed'}||0)*100
				 / $Global::total_started) }
		       @workers);
	if(length $status > $termcols) {
	    # 1:XX/XX/XX% 2:XX/XX/XX% 3:XX/XX/XX% 4:XX/XX/XX% 5:XX/XX/XX% 6:XX/XX/XX%
	    $header = "Computer:jobs running/jobs completed/%completed of all jobs";
	    $status = join(" ",map
			   { sprintf("%s:%d/%d/%d%%",
				     $workerno{$_}, $Global::host{$_}{'no_of_running'},
				     ($Global::host{$_}{'completed'}||0),
				     ($Global::host{$_}{'completed'}||0)*100
				     / $Global::total_started) }
			   @workers);
	}

    }
    if(length $status > $termcols) {
	# sshlogin1:XX/XX sshlogin2:XX/XX sshlogin3:XX/XX sshlogin4:XX/XX
	$header = "Computer:jobs running/jobs completed";
	$status = join(" ",map
		       { sprintf("%s:%d/%d",
				 $sshlogin{$_}, $Global::host{$_}{'no_of_running'},
				 ($Global::host{$_}{'completed'}||0)) }
		       @workers);
    }
    if(length $status > $termcols) {
	# 1:XX/XX 2:XX/XX 3:XX/XX 4:XX/XX 5:XX/XX 6:XX/XX
	$header = "Computer:jobs running/jobs completed";
	$status = join(" ",map
		       { sprintf("%s:%d/%d",
				 $workerno{$_}, $Global::host{$_}{'no_of_running'},
				 ($Global::host{$_}{'completed'}||0)) }
		       @workers);
    }
    if(length $status > $termcols) {
	# sshlogin1:XX sshlogin2:XX sshlogin3:XX sshlogin4:XX sshlogin5:XX
	$header = "Computer:jobs completed";
	$status = join(" ",map
		       { sprintf("%s:%d/%d",
				 $sshlogin{$_},
				 ($Global::host{$_}{'completed'}||0)) }
		       @workers);
    }
    if(length $status > $termcols) {
	# 1:XX 2:XX 3:XX 4:XX 5:XX 6:XX
	$header = "Computer:jobs completed";
	$status = join(" ",map
		       { sprintf("%s:%d/%d",
				 $workerno{$_},
				 ($Global::host{$_}{'completed'}||0)) }
		       @workers);
    }
    return ("workerlist" => $workerlist, "header" => $header, "status" => $status);
}

sub columns {
    # Get the number of columns of the display
    if(not $Global::columns) {
	$Global::columns = $ENV{'COLUMNS'};
	if(not $Global::columns) {
	    my $resize = qx{ resize 2>/dev/null };
	    $resize =~ /COLUMNS=(\d+);/ and do { $Global::columns = $1; };
	}
	$Global::columns ||= 80;
    }
    return $Global::columns;
}

sub start_more_jobs {
    my $jobs_started = 0;
    if(not $Global::StartNoNewJobs) {
	for my $sshlogin (keys %Global::host) {
	    debug("Running jobs on $sshlogin: $Global::host{$sshlogin}{'no_of_running'}\n");
	    while ($Global::host{$sshlogin}{'no_of_running'} <
		$Global::host{$sshlogin}{'max_no_of_running'}) {
		if(start_another_job($sshlogin) == 0) {
		    # No more jobs to start
		    last;
		}
		$Global::host{$sshlogin}{'no_of_running'}++;
		$jobs_started++;
	    }
	    debug("Running jobs on $sshlogin: $Global::host{$sshlogin}{'no_of_running'}\n");
	}
    }
    return $jobs_started;
}

sub start_another_job {
    # Grab a job from @Global::command, start it
    # and remember the pid, the STDOUT and the STDERR handles
    # Return 1.
    # If no more jobs: do nothing and return 0
    # Do we have enough file handles to start another job?
    my $sshlogin = shift;
    if(enough_file_handles()) {
	my $command = next_command_line_with_sshlogin($sshlogin);
	if(defined $command) {
	    debug("Command to run on '$sshlogin': $command\n");
	    my %jobinfo = start_job($command,$sshlogin);
	    if(%jobinfo) {
		$Global::running{$jobinfo{"pid"}} = \%jobinfo;
		return 1;
	    } else {
		# If interactive says: Dont run the job, then skip it and run the next
		return start_another_job($sshlogin);
	    }
	} else {
	    # No more commands to run
	    return 0;
	}
    } else {
	# No more file handles
	return 0;
    }
}

sub start_job {
    # Setup STDOUT and STDERR for a job and start it.
    my $command = shift;
    my $sshlogin = shift;
    my ($pid,$out,$err,%out,%err,$outname,$errname,$name);
    if($Global::grouped) {
	# To group we create temporary files for STDOUT and STDERR
	# Filehandles are global, so to not overwrite the filehandles use a hash with new keys
	# To avoid the cleanup unlink the files immediately (but keep them open)
	$outname = ++$Global::TmpFilename;
	($out{$outname},$name) = tempfile(SUFFIX => ".par");
	unlink $name;
	$errname = ++$Global::TmpFilename;
	($err{$errname},$name) = tempfile(SUFFIX => ".par");
	unlink $name;

	open STDOUT, '>&', $out{$outname} or die "Can't redirect STDOUT: $!";
	open STDERR, '>&', $err{$errname} or die "Can't dup STDOUT: $!";
    }

    if($Global::interactive or $Global::stderr_verbose) {
	if($Global::interactive) {
	    print $Global::original_stderr "$command ?...";
	    open(TTY,"/dev/tty") || die;
	    my $answer = <TTY>;
	    close TTY;
	    my $run_yes = ($answer =~ /^\s*y/i);
	    if (not $run_yes) {
		open STDOUT, ">&", $Global::original_stdout
		    or die "Can't dup \$oldout: $!";
		open STDERR, ">&", $Global::original_stderr
		    or die "Can't dup \$oldout: $!";
		return;
	    }
	} else {
	    print $Global::original_stderr "$command\n";
	}
    }
    if($Global::verbose and not $Global::grouped) {
	print STDOUT $command,"\n";
    }
    $Global::total_running++;
    $Global::total_started++;
    debug("$Global::total_running processes. Starting: $command\n");
    #print STDERR "LEN".length($command)."\n";
    $Global::job_start_sequence++;

    if($::opt_a and $Global::job_start_sequence == 1) {
	# Give STDIN to the first job if using -a
	$pid = open3("<&STDIN", ">&STDOUT", ">&STDERR", $command) ||
	    die("open3 failed. Report a bug to <bug-parallel\@gnu.org>\n");
	# Re-open to avoid complaining
	open STDIN, "<&", $Global::original_stdin
	    or die "Can't dup \$Global::original_stdin: $!";
    } else {
	$pid = open3(gensym, ">&STDOUT", ">&STDERR", $command) ||
	    die("open3 failed. Report a bug to <bug-parallel\@gnu.org>\n");
    }
    debug("started: $command\n");
    open STDOUT, ">&", $Global::original_stdout
	or die "Can't dup \$Global::original_stdout: $!";
    open STDERR, ">&", $Global::original_stderr
	or die "Can't dup \$Global::original_stderr: $!";

    if($Global::grouped) {
	return ("seq" => $Global::job_start_sequence,
		"pid" => $pid,
		"out" => $out{$outname},
		"err" => $err{$errname},
		"sshlogin" => $sshlogin,
		"command" => $command);
    } else {
	return ("seq" => $Global::job_start_sequence,
		"pid" => $pid,
		"sshlogin" => $sshlogin,
		"command" => $command);
    }
}

sub print_job {
    # Print the output of the jobs
    # Only relevant for grouping
    $Global::grouped or return;
    my $fhs = shift;
    if(not defined $fhs) {
	return;
    }
    my $out = $fhs->{out};
    my $err = $fhs->{err};
    my $command = $fhs->{command};

    debug(">>joboutput $command\n");
    if($Global::verbose and $Global::grouped) {
	print STDOUT $command,"\n";
	# If STDOUT and STDERR is merged, we want the command to be printed first
	# so flush to avoid STDOUT being buffered
	flush STDOUT;
    }
    seek $_, 0, 0 for $out, $err;
    if($Global::debug) {
	print STDERR "ERR:\n";
    }
    my $buf;
    while(sysread($err,$buf,1000_000)) {
	print STDERR $buf;
    }
    if($Global::debug) {
	print STDOUT "OUT:\n";
    }
    while(sysread($out,$buf,1000_000)) {
	print STDOUT $buf;
    }
    debug("<<joboutput $command\n");
    close $out;
    close $err;
}

#
# Remote ssh
#

sub read_sshloginfile {
    my $file = shift;
    open(IN, $file) || die "Cannot open $file";
    while(<IN>) {
	chomp;
	push @Global::sshlogin, $_;
    }
    close IN;
}

sub parse_sshlogin {
    my (@login);
    if(not @Global::sshlogin) { @Global::sshlogin = (":"); }
    for my $sshlogin (@Global::sshlogin) {
	# Split up -S sshlogin,sshlogin
	push (@login, (split /,/, $sshlogin));
    }
    for my $sshlogin (@login) {
	if($sshlogin =~ s:^(\d*)/::) {
	    # Override default autodetected ncpus unless zero or missing
	    if($1) {
		$Global::host{$sshlogin}{'ncpus'} = $1;
	    }
	}
	$Global::host{$sshlogin}{'no_of_running'} = 0;
	$Global::host{$sshlogin}{'maxlength'} = max_length_of_command_line();
    }
    debug("sshlogin: ", my_dump(%Global::host),"\n");
    if($::opt_transfer or @::opt_return or $::opt_cleanup or @::opt_basefile) {
	if(not remote_hosts()) {
	    # There are no remote hosts
	    if(defined @::opt_trc) {
		print STDERR "Warning: --trc ignored as there are no remote --sshlogin\n";
	    } elsif (defined $::opt_transfer) {
		print STDERR "Warning: --transfer ignored as there are no remote --sshlogin\n";
	    } elsif (defined @::opt_return) {
		print STDERR "Warning: --return ignored as there are no remote --sshlogin\n";
	    } elsif (defined $::opt_cleanup) {
		print STDERR "Warning: --cleanup ignored as there are no remote --sshlogin\n";
	    } elsif (defined @::opt_basefile) {
		print STDERR "Warning: --basefile ignored as there are no remote --sshlogin\n";
	    }
	}
    }
}

sub remote_hosts {
    # Return sshlogins that are not ':'
    return grep !/^:$/, keys %Global::host;
}

sub sshcommand_of_sshlogin {
    # 'server' -> ('ssh -S /tmp/parallel-ssh-RANDOM/host-','server')
    # 'user@server' -> ('ssh','user@server')
    # 'myssh user@server' -> ('myssh','user@server')
    # 'myssh -l user server' -> ('myssh -l user','server')
    # '/usr/local/bin/myssh -l user server' -> ('/usr/local/bin/myssh -l user','server')
    my $sshlogin = shift;
    my ($sshcmd, $serverlogin);
    if($sshlogin =~ /(.+) (\S+)$/) {
	# Own ssh command
	$sshcmd = $1; $serverlogin = $2;
    } else {
	# Normal ssh
	if($::opt_controlmaster) {
	    # Use control_path to make ssh faster
	    my $control_path = control_path_dir()."/ssh-%r@%h:%p";
	    $sshcmd = "ssh -S ".$control_path;
	    $serverlogin = $sshlogin;
	    #my $master = "ssh -MTS ".control_path_dir()."/ssh-%r@%h:%p ".$serverlogin;
	    my $master = "ssh -MTS ".control_path_dir()."/ssh-%r@%h:%p ".$serverlogin." sleep 1";
	    if(not $Global::control_path{$control_path}++) {
		my $pid = fork();
		if($pid) {
		    $Global::sshmaster{$pid}++;
		} else {
		    debug($master,"\n");
		    `$master`;
		    exit(0);
		}
	    }
	} else {
	    $sshcmd = "ssh"; $serverlogin = $sshlogin;
	}
    }
    return ($sshcmd, $serverlogin);
}

sub control_path_dir {
    if(not $Global::control_path_dir) {
	$Global::control_path_dir = tempdir("/tmp/parallel-ssh-XXXX", CLEANUP => 1 );
    }
    return $Global::control_path_dir;
}

sub sshtransfer {
    # Return the sshcommand needed to transfer the file
    return sshtransferreturn(@_,1,0);
}

sub sshreturn {
    # Return the sshcommand needed to returning the file
    my $removesource = $::opt_cleanup;
    return sshtransferreturn(@_,0,$removesource);
}

sub sshcleanup {
    # Return the sshcommand needed to remove the file
    my ($sshlogin,$file) = (@_);
    my ($sshcmd,$serverlogin) = sshcommand_of_sshlogin($sshlogin);
    return "$sshcmd $serverlogin rm -f ".shell_quote($file);
}

sub sshtransferreturn {
    my ($sshlogin,$file,$transfer,$removesource) = (@_);
    my ($sshcmd,$serverlogin) = sshcommand_of_sshlogin($sshlogin);
    my $rsync_opt = "-rlDzRE -e".shell_quote($sshcmd);
    $file =~ s:/\./:/:g; # Rsync treats /./ special. We dont want that
    $file =~ s:^\./::g; # Remove ./ if any
    my $relpath = ($file !~ m:^/:); # Is the path relative?
    # Use different subdirs depending on abs or rel path
    my $rsync_destdir = ($relpath ? "./" : "/");
    if($transfer) {
	# Abs path: rsync -rlDzRE /home/tange/dir/subdir/file.gz server:/
	# Rel path: rsync -rlDzRE ./subdir/file.gz server:./
	if($relpath) {
	    $file = "./".$file;
	}
	if(-r shell_unquote($file)) {
	    return "rsync $rsync_opt $file $serverlogin:$rsync_destdir";
	} else {
	    print STDERR "Warning: $file is not readable and will not be transferred\n";
	    return "true"; # dummy command to run
	}
    } else {
	my $noext = no_extension($file); # Remove .ext before prepending ./
	my @cmd = ();
	for my $ret_file (@Global::ret_files) {
	    my $remove = $removesource ? "--remove-source-files" : "";
	    # If relative path: prepend ./ (to avoid problems with ':')
	    my $replaced = ($relpath ? "./" : "") .
		context_replace($ret_file,[$file],[$noext]);
	    # --return
	    # Abs path: rsync -rlDzRE server:/home/tange/dir/subdir/file.gz /
	    # Rel path: rsync -rlDzRE server:./subsir/file.gz ./
	    push(@cmd, "rsync $rsync_opt $remove $serverlogin:"
		.shell_quote($replaced)." ".$rsync_destdir);
	}
	return join(";",@cmd);
    }
}

sub setup_basefile {
    # Transfer basefiles to each $sshlogin
    # This needs to be done before first jobs on $sshlogin is run
    # Can we do this in parallel?
    my $cmd = "";
    for my $sshlogin (keys %Global::host) {
	if($sshlogin eq ":") { next }
	my ($sshcmd,$serverlogin) = sshcommand_of_sshlogin($sshlogin);
	my $rsync_opt = "-rlDzR -e".shell_quote($sshcmd);
	for my $file (@::opt_basefile) {
	    my $f = $file;
	    my $relpath = ($f !~ m:^/:); # Is the path relative?
	    # Use different subdirs depending on abs or rel path
	    my $rsync_destdir = ($relpath ? "./" : "/");
	    $f =~ s:/\./:/:g; # Rsync treats /./ special. We dont want that
	    $f = shell_quote($f);
	    $cmd .= "rsync $rsync_opt $f $serverlogin:$rsync_destdir &";
	}
    }
    $cmd .= "wait;";
    debug("basesetup: $cmd\n");
    print `$cmd`;
}

sub cleanup_basefile {
    # Remove the basefiles transferred
    my $cmd="";
    for my $sshlogin (keys %Global::host) {
	if($sshlogin eq ":") { next }
	my ($sshcmd,$serverlogin) = sshcommand_of_sshlogin($sshlogin);
	for my $file (@::opt_basefile) {
	    $cmd .= "$sshcmd $serverlogin rm -f ".shell_quote(shell_quote($file))."&";
	}
    }
    $cmd .= "wait;";
    debug("basecleanup: $cmd\n");
    print `$cmd`;
}

#
# Signal handling
#

sub ListRunningJobs {
    for my $v (values %Global::running) {
	print STDERR "$Global::progname: ",$v->{'command'},"\n";
    }
}

sub StartNoNewJobs {
    print STDERR
	("$Global::progname: SIGTERM received. No new jobs will be started.\n",
	 "$Global::progname: Waiting for these ", scalar(keys %Global::running),
	 " jobs to finish. Send SIGTERM again to stop now.\n");
    ListRunningJobs();
    $Global::StartNoNewJobs++;
    $SIG{TERM} = $Global::original_sigterm;
}

sub CountSigChild {
    $Global::SigChildCaught++;
}

sub DoNotReap {
    # This will postpone SIGCHILD for sections that cannot be distracted by a dying child
    # (Racecondition)
    $SIG{CHLD} = \&CountSigChild;
}

sub ReapIfNeeded {
    # Do the postponed SIGCHILDs if any and re-install normal reaper for SIGCHILD
    # (Racecondition)
    if($Global::SigChildCaught) {
	$Global::SigChildCaught = 0;
	Reaper();
    }
    $SIG{CHLD} = \&Reaper;
}

sub Reaper {
    # A job finished.
    # Print the output.
    # Start another job
    DoNotReap();
    $Global::reaperlevel++;
    my $stiff;
    debug("Reaper called $Global::reaperlevel\n");
    while (($stiff = waitpid(-1, &WNOHANG)) > 0) {
	if($Global::sshmaster{$stiff}) {
	    # This is one of the ssh -M: ignore
	    next;
	}
	$Global::running{$stiff}{'exitstatus'} = $? >> 8;
	debug("died ($Global::running{$stiff}{'exitstatus'}): $Global::running{$stiff}{'seq'}");
	# Force printing now if the job failed and we are going to exit
	my $print_now = ($Global::running{$stiff}{'exitstatus'} and
	    $::opt_halt_on_error and $::opt_halt_on_error == 2);
	if($Global::keeporder and not $print_now) {
	    $Global::print_later{$Global::running{$stiff}{"seq"}} =
		$Global::running{$stiff};
	    while($Global::print_later{$Global::job_end_sequence}) {
		debug("Found job end $Global::job_end_sequence");
		print_job($Global::print_later{$Global::job_end_sequence});
		delete $Global::print_later{$Global::job_end_sequence};
		$Global::job_end_sequence++;
	    }
	} else {
	    print_job ($Global::running{$stiff});
	}
	if($Global::running{$stiff}{'exitstatus'}) {
	    # The jobs had a exit status <> 0, so error
	    $Global::exitstatus++;
	    if($::opt_halt_on_error) {
		if($::opt_halt_on_error == 1) {
		    # If halt on error == 1 we should gracefully exit
		    print STDERR ("$Global::progname: Starting no more jobs. ",
				  "Waiting for ", scalar(keys %Global::running),
				  " jobs to finish. This job failed:\n",
				  $Global::running{$stiff}{"command"},"\n");
		    $Global::StartNoNewJobs++;
		    $Global::halt_on_error_exitstatus = $Global::running{$stiff}{'exitstatus'};
		} elsif($::opt_halt_on_error == 2) {
		    # If halt on error == 2 we should exit immediately
		    print STDERR ("$Global::progname: This job failed:\n",
				  $Global::running{$stiff}{"command"},"\n");
		    exit ($Global::running{$stiff}{'exitstatus'});
		}
	    }
	}
	my $sshlogin = $Global::running{$stiff}{'sshlogin'};
	$Global::host{$sshlogin}{'no_of_running'}--;
	$Global::host{$sshlogin}{'completed'}++;
	$Global::total_running--;
	$Global::total_completed++;
	delete $Global::running{$stiff};
	start_more_jobs();
    }
    ReapIfNeeded();
    debug("Reaper exit $Global::reaperlevel\n");
    $Global::reaperlevel--;
}

#
# Usage
#

sub die_usage {
    usage();
    exit(255);
}

sub usage {
    print "Usage:\n";
    print "$Global::progname [options] [command [arguments]] < list_of_arguments\n";
    print "\n";
    print "See 'man $Global::progname' for the options\n";
}

sub version {
    print join("\n",
	       "$Global::progname $Global::version",
	       "Copyright (C) 2007,2008,2009,2010 Ole Tange and Free Software Foundation, Inc.",
	       "License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>",
	       "This is free software: you are free to change and redistribute it.",
	       "$Global::progname comes with no warranty.",
	       "",
	       "Web site: http://www.gnu.org/software/${Global::progname}\n"
	);
}

sub show_limits {
    print("Maximal size of command: ",real_max_length(),"\n",
	  "Maximal used size of command: ",max_length_of_command_line(),"\n",
	  "\n",
	  "Execution of  will continue now, and it will try to read its input\n",
	  "and run commands; if this is not what you wanted to happen, please\n",
	  "press CTRL-D or CTRL-C\n");
}


#
# Debugging
#

sub debug {
    $Global::debug or return;
    if($Global::original_stdout) {
	print $Global::original_stdout @_;
    } else {
	print @_;
    }
}

sub my_memory_usage {
    use strict;
    use FileHandle;


    my $pid = $$;
    if(-e "/proc/$pid/stat") {
	my $fh = FileHandle->new("</proc/$pid/stat");

	my $data = <$fh>;
	chomp $data;
	$fh->close;

	my @procinfo = split(/\s+/,$data);

	return $procinfo[22];
    } else {
	return 0;
    }
}

sub my_size {
    my @size_this = (@_);
    eval "use Devel::Size qw(size total_size)";
    if ($@) {
	return -1;
    } else {
	return total_size(@_);
    }
}


sub my_dump {
    my @dump_this = (@_);
    eval "use Data::Dump qw(dump);";
    if ($@) {
        # Data::Dump not installed
        eval "use Data::Dumper;";
        if ($@) {
            my $err =  "Neither Data::Dump nor Data::Dumper is installed\n".
                "Not dumping output\n";
            print STDERR $err;
            return $err;
        } else {
            return Dumper(@dump_this);
        }
    } else {
        eval "use Data::Dump qw(dump);";
        return (Data::Dump::dump(@dump_this));
    }
}

# Keep perl -w happy
$main::opt_u = $main::opt_e = $main::opt_c = $main::opt_f =
$main::opt_q = $main::opt_0 = $main::opt_s = $main::opt_v =
$main::opt_g = $main::opt_P = $main::opt_D = $main::opt_m =
$main::opt_X = $main::opt_x = $main::opt_k = $main::opt_d =
$main::opt_P = $main::opt_i = $main::opt_p = $main::opt_a =
$main::opt_version = $main::opt_L = $main::opt_l =
$main::opt_show_limits = $main::opt_n = $main::opt_e = $main::opt_verbose =
$main::opt_E = $main::opt_r = $Global::xargs = $Global::keeporder =
$Global::control_path = 0;

# Hvordan udregnes system limits på remote systems hvis jeg ikke ved, hvormange
# argumenter, der er? Lav system limits lokalt og lad det være max

# TODO max_line_length on remote
# TODO compute how many can be transferred within max_line_length
# TODO Unittest with filename that is long and requires a lot of quoting. Will there be to many
# TODO --max-number-of-jobs print the system limited number of jobs

# TODO Debian package

# TODO to kill from a run script parallel should set PARALLEL_PID that can be sig termed
# TAGS: parallel | parallel processing | multicore | multiprocessor | Clustering/Distributed Networks
# job control | multiple jobs | parallelization | text processing | cluster | filters
# Clustering Tools | Command Line Tools | Utilities | System Administration
# Bash parallel
