Code cleanup. POD file for mini man page for sem

autom4te.cache/output.0

@@ -1,6 +1,6 @@
 @%:@! /bin/sh
 @%:@ Guess values for system-dependent variables and create Makefiles.
-@%:@ Generated by GNU Autoconf 2.65 for parallel 20100722.
+@%:@ Generated by GNU Autoconf 2.65 for parallel 20100817.
 @%:@
 @%:@ Report bugs to <bug-parallel@gnu.org>.
 @%:@ 
@@ -551,8 +551,8 @@ MAKEFLAGS=
 # Identity of this package.
 PACKAGE_NAME='parallel'
 PACKAGE_TARNAME='parallel'
-PACKAGE_VERSION='20100722'
+PACKAGE_VERSION='20100817'
-PACKAGE_STRING='parallel 20100722'
+PACKAGE_STRING='parallel 20100817'
 PACKAGE_BUGREPORT='bug-parallel@gnu.org'
 PACKAGE_URL=''
 
@@ -1167,7 +1167,7 @@ if test "$ac_init_help" = "long"; then
   # Omit some internal or obsolete options to make the list less imposing.
   # This message is too long to be a string in the A/UX 3.1 sh.
   cat <<_ACEOF
-\`configure' configures parallel 20100722 to adapt to many kinds of systems.
+\`configure' configures parallel 20100817 to adapt to many kinds of systems.
 
 Usage: $0 [OPTION]... [VAR=VALUE]...
 
@@ -1233,7 +1233,7 @@ fi
 
 if test -n "$ac_init_help"; then
   case $ac_init_help in
-     short | recursive ) echo "Configuration of parallel 20100722:";;
+     short | recursive ) echo "Configuration of parallel 20100817:";;
    esac
   cat <<\_ACEOF
 
@@ -1300,7 +1300,7 @@ fi
 test -n "$ac_init_help" && exit $ac_status
 if $ac_init_version; then
   cat <<\_ACEOF
-parallel configure 20100722
+parallel configure 20100817
 generated by GNU Autoconf 2.65
 
 Copyright (C) 2009 Free Software Foundation, Inc.
@@ -1317,7 +1317,7 @@ cat >config.log <<_ACEOF
 This file contains any messages produced by compilers while
 running configure, to aid debugging if configure makes a mistake.
 
-It was created by parallel $as_me 20100722, which was
+It was created by parallel $as_me 20100817, which was
 generated by GNU Autoconf 2.65.  Invocation command line was
 
   $ $0 $@
@@ -2125,7 +2125,7 @@ fi
 
 # Define the identity of the package.
  PACKAGE='parallel'
- VERSION='20100722'
+ VERSION='20100817'
 
 
 cat >>confdefs.h <<_ACEOF
@@ -2675,7 +2675,7 @@ cat >>$CONFIG_STATUS <<\_ACEOF || ac_write_fail=1
 # report actual input values of CONFIG_FILES etc. instead of their
 # values after options handling.
 ac_log="
-This file was extended by parallel $as_me 20100722, which was
+This file was extended by parallel $as_me 20100817, which was
 generated by GNU Autoconf 2.65.  Invocation command line was
 
   CONFIG_FILES    = $CONFIG_FILES
@@ -2737,7 +2737,7 @@ _ACEOF
 cat >>$CONFIG_STATUS <<_ACEOF || ac_write_fail=1
 ac_cs_config="`$as_echo "$ac_configure_args" | sed 's/^ //; s/[\\""\`\$]/\\\\&/g'`"
 ac_cs_version="\\
-parallel config.status 20100722
+parallel config.status 20100817
 configured by $0, generated by GNU Autoconf 2.65,
   with options \\"\$ac_cs_config\\"
 

autom4te.cache/output.1

@@ -1,6 +1,6 @@
 @%:@! /bin/sh
 @%:@ Guess values for system-dependent variables and create Makefiles.
-@%:@ Generated by GNU Autoconf 2.65 for parallel 20100722.
+@%:@ Generated by GNU Autoconf 2.65 for parallel 20100817.
 @%:@
 @%:@ Report bugs to <bug-parallel@gnu.org>.
 @%:@ 
@@ -551,8 +551,8 @@ MAKEFLAGS=
 # Identity of this package.
 PACKAGE_NAME='parallel'
 PACKAGE_TARNAME='parallel'
-PACKAGE_VERSION='20100722'
+PACKAGE_VERSION='20100817'
-PACKAGE_STRING='parallel 20100722'
+PACKAGE_STRING='parallel 20100817'
 PACKAGE_BUGREPORT='bug-parallel@gnu.org'
 PACKAGE_URL=''
 
@@ -1167,7 +1167,7 @@ if test "$ac_init_help" = "long"; then
   # Omit some internal or obsolete options to make the list less imposing.
   # This message is too long to be a string in the A/UX 3.1 sh.
   cat <<_ACEOF
-\`configure' configures parallel 20100722 to adapt to many kinds of systems.
+\`configure' configures parallel 20100817 to adapt to many kinds of systems.
 
 Usage: $0 [OPTION]... [VAR=VALUE]...
 
@@ -1233,7 +1233,7 @@ fi
 
 if test -n "$ac_init_help"; then
   case $ac_init_help in
-     short | recursive ) echo "Configuration of parallel 20100722:";;
+     short | recursive ) echo "Configuration of parallel 20100817:";;
    esac
   cat <<\_ACEOF
 
@@ -1300,7 +1300,7 @@ fi
 test -n "$ac_init_help" && exit $ac_status
 if $ac_init_version; then
   cat <<\_ACEOF
-parallel configure 20100722
+parallel configure 20100817
 generated by GNU Autoconf 2.65
 
 Copyright (C) 2009 Free Software Foundation, Inc.
@@ -1317,7 +1317,7 @@ cat >config.log <<_ACEOF
 This file contains any messages produced by compilers while
 running configure, to aid debugging if configure makes a mistake.
 
-It was created by parallel $as_me 20100722, which was
+It was created by parallel $as_me 20100817, which was
 generated by GNU Autoconf 2.65.  Invocation command line was
 
   $ $0 $@
@@ -2125,7 +2125,7 @@ fi
 
 # Define the identity of the package.
  PACKAGE='parallel'
- VERSION='20100722'
+ VERSION='20100817'
 
 
 cat >>confdefs.h <<_ACEOF
@@ -2675,7 +2675,7 @@ cat >>$CONFIG_STATUS <<\_ACEOF || ac_write_fail=1
 # report actual input values of CONFIG_FILES etc. instead of their
 # values after options handling.
 ac_log="
-This file was extended by parallel $as_me 20100722, which was
+This file was extended by parallel $as_me 20100817, which was
 generated by GNU Autoconf 2.65.  Invocation command line was
 
   CONFIG_FILES    = $CONFIG_FILES
@@ -2737,7 +2737,7 @@ _ACEOF
 cat >>$CONFIG_STATUS <<_ACEOF || ac_write_fail=1
 ac_cs_config="`$as_echo "$ac_configure_args" | sed 's/^ //; s/[\\""\`\$]/\\\\&/g'`"
 ac_cs_version="\\
-parallel config.status 20100722
+parallel config.status 20100817
 configured by $0, generated by GNU Autoconf 2.65,
   with options \\"\$ac_cs_config\\"
 

autom4te.cache/traces.1

@@ -1,4 +1,4 @@
-m4trace:configure.ac:1: -1- AC_INIT([parallel], [20100722], [bug-parallel@gnu.org])
+m4trace:configure.ac:1: -1- AC_INIT([parallel], [20100817], [bug-parallel@gnu.org])
 m4trace:configure.ac:1: -1- m4_pattern_forbid([^_?A[CHUM]_])
 m4trace:configure.ac:1: -1- m4_pattern_forbid([_AC_])
 m4trace:configure.ac:1: -1- m4_pattern_forbid([^LIBOBJS$], [do not use LIBOBJS directly, use AC_LIBOBJ (see section `AC_LIBOBJ vs LIBOBJS'])

configure

@@ -1,6 +1,6 @@
 #! /bin/sh
 # Guess values for system-dependent variables and create Makefiles.
-# Generated by GNU Autoconf 2.65 for parallel 20100722.
+# Generated by GNU Autoconf 2.65 for parallel 20100817.
 #
 # Report bugs to <bug-parallel@gnu.org>.
 #
@@ -551,8 +551,8 @@ MAKEFLAGS=
 # Identity of this package.
 PACKAGE_NAME='parallel'
 PACKAGE_TARNAME='parallel'
-PACKAGE_VERSION='20100722'
+PACKAGE_VERSION='20100817'
-PACKAGE_STRING='parallel 20100722'
+PACKAGE_STRING='parallel 20100817'
 PACKAGE_BUGREPORT='bug-parallel@gnu.org'
 PACKAGE_URL=''
 
@@ -1167,7 +1167,7 @@ if test "$ac_init_help" = "long"; then
   # Omit some internal or obsolete options to make the list less imposing.
   # This message is too long to be a string in the A/UX 3.1 sh.
   cat <<_ACEOF
-\`configure' configures parallel 20100722 to adapt to many kinds of systems.
+\`configure' configures parallel 20100817 to adapt to many kinds of systems.
 
 Usage: $0 [OPTION]... [VAR=VALUE]...
 
@@ -1233,7 +1233,7 @@ fi
 
 if test -n "$ac_init_help"; then
   case $ac_init_help in
-     short | recursive ) echo "Configuration of parallel 20100722:";;
+     short | recursive ) echo "Configuration of parallel 20100817:";;
    esac
   cat <<\_ACEOF
 
@@ -1300,7 +1300,7 @@ fi
 test -n "$ac_init_help" && exit $ac_status
 if $ac_init_version; then
   cat <<\_ACEOF
-parallel configure 20100722
+parallel configure 20100817
 generated by GNU Autoconf 2.65
 
 Copyright (C) 2009 Free Software Foundation, Inc.
@@ -1317,7 +1317,7 @@ cat >config.log <<_ACEOF
 This file contains any messages produced by compilers while
 running configure, to aid debugging if configure makes a mistake.
 
-It was created by parallel $as_me 20100722, which was
+It was created by parallel $as_me 20100817, which was
 generated by GNU Autoconf 2.65.  Invocation command line was
 
   $ $0 $@
@@ -2125,7 +2125,7 @@ fi
 
 # Define the identity of the package.
  PACKAGE='parallel'
- VERSION='20100722'
+ VERSION='20100817'
 
 
 cat >>confdefs.h <<_ACEOF
@@ -2675,7 +2675,7 @@ cat >>$CONFIG_STATUS <<\_ACEOF || ac_write_fail=1
 # report actual input values of CONFIG_FILES etc. instead of their
 # values after options handling.
 ac_log="
-This file was extended by parallel $as_me 20100722, which was
+This file was extended by parallel $as_me 20100817, which was
 generated by GNU Autoconf 2.65.  Invocation command line was
 
   CONFIG_FILES    = $CONFIG_FILES
@@ -2737,7 +2737,7 @@ _ACEOF
 cat >>$CONFIG_STATUS <<_ACEOF || ac_write_fail=1
 ac_cs_config="`$as_echo "$ac_configure_args" | sed 's/^ //; s/[\\""\`\$]/\\\\&/g'`"
 ac_cs_version="\\
-parallel config.status 20100722
+parallel config.status 20100817
 configured by $0, generated by GNU Autoconf 2.65,
   with options \\"\$ac_cs_config\\"
 

configure.ac

@@ -1,4 +1,4 @@
-AC_INIT([parallel], [20100722], [bug-parallel@gnu.org])
+AC_INIT([parallel], [20100817], [bug-parallel@gnu.org])
 AM_INIT_AUTOMAKE([-Wall -Werror foreign])
 AC_CONFIG_HEADERS([config.h])
 AC_CONFIG_FILES([

doc/FUTURE_IDEAS

@@ -1,11 +1,16 @@
-# sem -j+0
+# Examples of sem
-# sem gzip foo ";" echo done
+
+Weird bug - only interactive
+
+echo '### BUG: Test --fg followed by --bg'
+parallel -u --fg --semaphore seq 1 10 '|' pv -qL 20
+parallel -u --bg --semaphore seq 11 20 '|' pv -qL 20
+parallel -u --fg --semaphore seq 21 30 '|' pv -qL 20
+parallel -u --bg --semaphore seq 31 40 '|' pv -qL 20
+sem --wait
+
+find . -execdir sem -j100 'sleep 4; echo {}' \; ; sem --wait
 
-# Allow 7 to run. After then 7th is started, block untill one is dead
-parallel --semaphore --id uniqidentifier -j7 command
-parallel --semaphore  -j7 command
-mdm.screen find dir -execdir mdm-run cmd {} \;
-find dir -execdir parallel --semaphore cmd {} \;
 
 fex syntax for splitting fields
 http://www.semicomplete.com/projects/fex/

doc/release_new_version

@@ -79,7 +79,9 @@ Newsgroups: comp.unix.shell,comp.unix.admin
 <<<<<
 to:parallel@gnu.org, bug-parallel@gnu.org, info-gnu@gnu.org, bug-directory@gnu.org
 cc:Peter Simons <simons@cryp.to>, Sandro Cazzaniga <kharec@mandriva.org>,
-   Tim Cuthbertson <tim3d.junk@gmail.com>
+   Tim Cuthbertson <tim3d.junk@gmail.com>, Ludovic Courtès <ludo@gnu.org>,
+   Markus Ammer <mkmm@gmx-topmail.de>, Pavel Nuzhdin <pnzhdin@gmail.com>,
+   ((psung@alum.mit.edu))
 
 Subject: GNU Parallel 20100722 released
 
@@ -88,12 +90,15 @@ download at: http://ftp.gnu.org/gnu/parallel/
 
 New in this release:
 
+* Counting semaphore functionality: start a job in the background. If
+  N jobs are already running, wait for one to complete.
+
 * With --colsep a table can be used as input. Example:
   cat tab_sep_table | parallel --colsep '\t' echo col1 {1} col2 {2}
 
 * --trim can remove white space around arguments.
 
-* NixOS package. Thanks to Ludovic Courtès <ludo at gnu dot org>
+* --sshloginfile '..' means use ~/.parallel/sshloginfile
 
 * Zero install package. Thanks to Tim Cuthbertson <tim3d dot junk at
   gmail dot com>
@@ -101,11 +106,13 @@ New in this release:
 * OpenSUSE package. Thanks to Markus Ammer <mkmm at gmx-topmail dot
   de>
 
+* NixOS package. Thanks to Ludovic Courtès <ludo at gnu dot org>
+
 * Web review http://oentend.blogspot.com/2010/08/gnu-parallel.html
   Thanks to Pavel Nuzhdin <pnzhdin at gmail dot com>
 
 * Web review http://psung.blogspot.com/2010/08/gnu-parallel.html
-  Thanks to Phil Sung
+  Thanks to Phil Sung ((<psung at alum dot mit dot edu>))
 
 
 = About GNU Parallel =

src/parallel

@@ -184,7 +184,7 @@ Multiple B<-B> can be specified to transfer more basefiles. The
 I<file> will be transferred the same way as B<--transfer>.
 
 
-=item B<--bg> (not implemented)
+=item B<--bg> (beta testing)
 
 Run command in background thus GNU B<parallel> will not wait for
 completion of the command before exiting. This is the default if
@@ -281,7 +281,7 @@ jobs. GNU B<parallel> normally only reads the next job to run.
 Implies B<--progress>.
 
 
-=item B<--fg> (not implemented)
+=item B<--fg> (beta testing)
 
 Run command in foreground thus GNU B<parallel> will wait for
 completion of the command before exiting.
@@ -606,7 +606,7 @@ operating system and the B<-s> option.  Pipe the input from /dev/null
 to do anything.
 
 
-=item B<--semaphore> (not implemented)
+=item B<--semaphore> (beta testing)
 
 Work as a counting semaphore. B<--semaphore> will cause GNU
 B<parallel> to start I<command> in the background. When the number of
@@ -623,9 +623,9 @@ Used with B<--fg>, B<--wait>, and B<--semaphorename>.
 The command B<sem> is an alias for B<parallel --semaphore>.
 
 
-=item B<--semaphorename> I<name> (not implemented)
+=item B<--semaphorename> I<name> (beta testing)
 
-=item B<--id> I<name> (not implemented)
+=item B<--id> I<name>
 
 The name of the semaphore to use. The semaphore can be shared between
 multiple processes.
@@ -817,7 +817,7 @@ B<--silent>. See also B<-t>.
 Print the version GNU B<parallel> and exit.
 
 
-=item B<--wait> (not implemented)
+=item B<--wait> (beta testing)
 
 Wait for all commands to complete.
 
@@ -856,6 +856,8 @@ FUBAR in all files in this dir and subdirs:
 
 B<find . -type f -print0 | parallel -q0 perl -i -pe 's/FOO BAR/FUBAR/g'>
 
+Note B<-q> is needed because of the space in 'FOO BAR'.
+
 
 =head1 EXAMPLE: Reading arguments from command line
 
@@ -1658,12 +1660,16 @@ B<8> pexec -n 8 -r *.jpg -y unix -e IMG -c \
   jpegtopnm | pnmscale 0.5 | pnmtojpeg | \
   pexec -j -m blockwrite -s th_$IMG'
 
-B<8> GNU B<parallel> does not support mutexes directly but uses B<mutex> to
+B<8> Combining GNU B<parallel> and GNU B<sem>.
-do that.
 
-B<8> ls *jpg | parallel -j8 'mutex -m blockread cat {} | jpegtopnm |' \
+B<8> ls *jpg | parallel -j8 'sem --id blockread cat {} | jpegtopnm |' \
-  'pnmscale 0.5 | pnmtojpeg | mutex -m blockwrite cat > th_{}'
+  'pnmscale 0.5 | pnmtojpeg | sem --id blockwrite cat > th_{}'
 
+B<8> If reading and writing is done to the same disk, this may be
+faster as only one process will be either reading or writing:
+
+B<8> ls *jpg | parallel -j8 'sem --id diskio cat {} | jpegtopnm |' \
+  'pnmscale 0.5 | pnmtojpeg | sem --id diskio cat > th_{}'
 
 =head2 DIFFERENCES BETWEEN xjobs AND GNU Parallel
 
@@ -1749,6 +1755,7 @@ B<seq 1 19 | parallel -j+0 buffon -o - | sort -n >>B< result>
 
 B<cat files | parallel -j+0 cmd>
 
+B<find dir -execdir sem -j+0 cmd {} \;>
 
 =head2 DIFFERENCES BETWEEN xapply AND GNU Parallel
 
@@ -1823,10 +1830,9 @@ B<cat hostlist | parallel ssh {} do_stuff>
 
 =head1 BUGS
 
-Filenames beginning with '-' can cause some commands to give
+=head2 Quoting of newline
-unexpected results, as it will often be interpreted as an option.
 
-Because the way newline is quoted this will not work:
+Because of the way newline is quoted this will not work:
 
 echo 1,2,3 | parallel -vkd, "echo 'a{}'"
 
@@ -1834,6 +1840,11 @@ However, this will work:
 
 echo 1,2,3 | parallel -vkd, echo a{}
 
+=head2 Startup speed
+
+GNU B<parallel> is slow at starting up. Half of the startup time is
+spent finding the maximal length of a command line. Setting B<-s> will
+remove this part of the startup time.
 
 =head1 REPORTING BUGS
 
@@ -1987,16 +1998,16 @@ use strict;
 do_not_reap();
 parse_options();
 init_run_jobs();
+my $sem;
 if($Global::semaphore) {
-    run_as_semaphore();
+    $sem = acquire_semaphore();
-} else {
-    start_more_jobs();
 }
+start_more_jobs();
 reap_if_needed();
 drain_job_queue();
 cleanup();
 if($Global::semaphore) {
-    exit $Global::exitstatus;
+    $sem->release();
 }
 if($::opt_halt_on_error) {
     wait_and_exit($Global::halt_on_error_exitstatus);
@@ -2004,39 +2015,37 @@ if($::opt_halt_on_error) {
     wait_and_exit(min($Global::exitstatus,254));
 }
 
-sub run_as_semaphore {
+sub acquire_semaphore {
+    # Acquires semaphore. If needed: spawns to the background
+    # Returns:
+    #    The semaphore to be released when jobs is complete
     my $sem = Semaphore->new($Semaphore::name,$Global::host{':'}{'max_no_of_running'});
     $sem->acquire();
     debug("run");
     $Global::argfile = open_or_exit("/dev/null");
     unget_arg("");
     if($Semaphore::fg) {
-	start_more_jobs();
+	# skip
-	$sem->release();
     } else {
 	# If run in the background, the PID will change
 	# therefore release and re-acquire the semaphore
 	$sem->release();
-	if(not fork()) {
+	if(fork()) {
+	    exit(0);
+	} else {
 	    # child
 	    # Get a semaphore for this pid
-	    my $child_sem = Semaphore->new($Semaphore::name,$Global::host{':'}{'max_no_of_running'});
+	    $sem = Semaphore->new($Semaphore::name,$Global::host{':'}{'max_no_of_running'});
-	    $child_sem->acquire();
+	    $sem->acquire();
-	    start_more_jobs();
-	    reap_if_needed();
-	    drain_job_queue();
-	    cleanup();
-	    $child_sem->release();
-	} else {
-	    exit(0);
 	}
     }
+    return $sem;
 }
 
 sub parse_options {
     # Returns: N/A
     # Defaults:
-    $Global::version = 20100722;
+    $Global::version = 20100817;
     $Global::progname = 'parallel';
     $Global::debug = 0;
     $Global::verbose = 0;
@@ -4289,6 +4298,7 @@ sub new {
     -d $parallel_locks or mkdir $parallel_locks;
     my $lockdir = "$parallel_locks/$id";
     my $lockfile = $lockdir.".lock";
+    if($count < 1) { die "Semaphore count = $count"; }
     return bless {
 	'lockfile' => $lockfile,
 	'lockfh' => Symbol::gensym(),

src/sem.pod

@@ -0,0 +1,430 @@
+#!/usr/bin/perl -w
+
+=head1 NAME
+
+sem - semaphore for executing shell command lines in parallel
+
+=head1 SYNOPSIS
+
+B<sem> [--fg] [--id <id>] [--timeout <secs>] [-j <num>] [--wait] command
+
+=head1 DESCRIPTION
+
+GNU B<sem> is an alias for GNU B<parallel --semaphore>.
+
+It works as a tool for executing shell commands in parallel. GNU
+B<sem> acts as a counting semaphore. When GNU B<sem> is called with
+command it will start the command in the background. When I<num>
+number of commands are running in the background, GNU B<sem> will wait
+for one of these to complete before starting another command.
+
+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<sem> is capable of.
+
+=head1 OPTIONS
+
+=over 9
+
+=item I<command>
+
+Command to execute. The command may be followed by arguments for the command.
+
+
+=item B<--count> I<N>
+
+=item B<-j> I<N>
+
+Run up to N commands in parallel. Default is 1 thus acting like a
+mutex.
+
+
+=item B<--id> I<id>
+
+=item B<-i> I<id>
+
+Use B<id> as the name of the semaphore. Default is the name of the
+controlling tty (output from B<tty>).
+
+The default normally works as expected when used interactively, but
+when used in a script I<id> should be set. $$ is often a good value.
+
+
+=item B<--fg>
+
+Do not put command in background.
+
+
+=item B<--timeout> I<secs> (not implemented)
+
+=item B<-t> I<secs> (not implemented)
+
+If the semaphore is not released within I<secs> seconds, take it anyway.
+
+
+=item B<--wait>
+
+=item B<-w>
+
+Wait for all commands to complete.
+
+=back
+
+=head1 EXAMPLE: Gzipping *.log
+
+  for i in `ls *.log` ; do
+    echo $i
+    sem gzip $i ";" echo done
+  done
+  sem --wait
+
+
+=head1 BUGS
+
+Quoting and composed commands are not working.
+
+
+=head1 REPORTING BUGS
+
+Report bugs to <bug-parallel@gnu.org>.
+
+
+=head1 AUTHOR
+
+Copyright (C) 2010 Ole Tange, http://ole.tange.dk and Free Software
+Foundation, Inc.
+
+
+=head1 LICENSE
+
+Copyright (C) 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<sem> uses Perl, and the Perl modules Getopt::Long, 
+Symbol, Fcntl.
+
+
+=head1 SEE ALSO
+
+B<parallel>(1)
+
+=cut
+
+use strict;
+use Symbol qw(gensym);
+use Getopt::Long;
+
+Getopt::Long::Configure ("bundling","require_order");
+GetOptions("debug|D" => \$::opt_D,
+	   "id|i=s" => \$::opt_id,
+	   "count|j=i" => \$::opt_count,
+	   "fg" => \$::opt_fg,
+	   "timeout|t=i" => \$::opt_timeout,
+	   "version" => \$::opt_version,
+	   "wait|w" => \$::opt_wait,
+    ) || die_usage();
+$Global::debug = $::opt_D;
+$Global::version = 20100814;
+$Global::progname = 'sem';
+
+my $count = 1; # Default 1 = mutex
+if($::opt_count) {
+    $count = $::opt_count + 1;
+}
+if($::opt_wait) {
+    $count = 1;
+}
+my $id = $::opt_id;
+my $fg = $::opt_fg || $::opt_wait;
+$::opt_timeout = $::opt_timeout;
+if(defined $::opt_version) {
+    version();
+}
+
+if(not defined $id) {
+    # $id = getppid(); 
+    # does not work with: 
+    # find .  -name '*linux*' -exec sem -j1000 "sleep 3; echo `tty` '{}'" \; ; sem --wait echo done
+    $id = `tty`;
+}
+$id = "id-$id";
+$id=~s/([^-_a-z0-9])/unpack("H*",$1)/ige; # Convert non-word chars to hex
+my $sem = Semaphore->new($id,$count);
+$sem->acquire();
+debug("run");
+if($fg) {
+    system @ARGV;
+    $sem->release();
+} else {
+    # If run in the background, the PID will change
+    # therefore release and re-acquire the semaphore
+    $sem->release();
+    if(not fork()) {
+	# child
+	# Get a semaphore for this pid
+	my $child_sem = Semaphore->new($id,$count);
+	$child_sem->acquire();
+	system @ARGV;
+	$child_sem->release();
+    }
+}
+
+sub version {
+    # Returns: N/A
+    print join("\n",
+	       "GNU $Global::progname $Global::version",
+	       "Copyright (C) 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.",
+	       "GNU $Global::progname comes with no warranty.",
+	       "",
+	       "Web site: http://www.gnu.org/software/parallel\n"
+	);
+}
+
+sub usage {
+    # Returns: N/A
+    print "Usage:\n";
+    print "$Global::progname [options] [command [arguments]] < list_of_arguments)\n";
+    print "$Global::progname [options] [command [arguments]] ::: arguments\n";
+    print "$Global::progname [options] [command [arguments]] :::: argfile(s)\n";
+    print "\n";
+    print "See 'man $Global::progname' for the options\n";
+}
+
+sub die_usage {
+    usage();
+    exit(255);
+}
+
+sub debug {
+    # Returns: N/A
+    $Global::debug or return;
+    @_ = grep { defined $_ ? $_ : "" } @_;
+    print map {$_,"\n" } @_;
+}
+
+package Semaphore;
+
+# This package provides a counting semaphore
+#
+# If a process dies without releasing the semaphore the next process
+# that needs that entry will clean up dead semaphores
+#
+# The semaphores are stored in ~/.parallel/semaphores/id-<name> Each
+# file in ~/.parallel/semaphores/id-<name>/ is the process ID of the
+# process holding the entry. If the process dies, the entry can be
+# taken by another process.
+
+use Fcntl qw(:DEFAULT :flock);
+
+sub new {
+    my $class = shift;
+    my $id = shift;
+    my $count = shift;
+    my $parallel_locks = $ENV{'HOME'}."/.parallel/semaphores";
+    -d $parallel_locks or mkdir $parallel_locks;
+    my $lockdir = "$parallel_locks/$id";
+    my $lockfile = $lockdir.".lock";
+    return bless {
+	'lockfile' => $lockfile,
+	'lockfh' => Symbol::gensym(),
+	'lockdir' => $lockdir,
+	'id' => $id,
+	'idfile' => $lockdir."/".$id,
+	'pid' => $$,
+	'pidfile' => $lockdir."/".$$,
+	'count' => $count
+    }, ref($class) || $class;
+}
+
+sub acquire {
+    my $self = shift;
+    while(1) {
+	$self->atomic_link_if_count_less_than() and last;
+	::debug("Remove dead locks");
+	my $lockdir = $self->{'lockdir'};
+	for my $d (<$lockdir/*>) {
+	    $d =~ m:$lockdir/([0-9]+):o or next;
+	    if(not kill 0, $1) {
+		::debug("Dead: $d");
+		unlink $d;
+	    } else {
+		::debug("Alive: $d");
+	    }
+	}
+	# try again
+	$self->atomic_link_if_count_less_than() and last;
+	sleep 1;
+	# TODO if timeout: last
+    }
+    ::debug("got $self->{'pid'}");
+}
+
+sub release {
+    my ($self) = shift;
+    unlink $self->{'pidfile'};
+    if($self->nlinks() == 1) {
+	# This is the last link, so atomic cleanup
+	$self->lock();
+	if($self->nlinks() == 1) {
+	    unlink $self->{'idfile'};
+	    rmdir $self->{'lockdir'};
+	} 
+	$self->unlock();
+    }
+    ::debug("released $self->{'pid'}");
+}
+
+
+sub atomic_link_if_count_less_than {
+    # Link $file1 to $file2 if nlinks to $file1 < $count
+    my ($self) = shift;
+    my ($retval) = 0;
+    $self->lock();
+    if($self->nlinks() < $count) {
+	-d $self->{'lockdir'} || mkdir $self->{'lockdir'};
+	if(not -e $self->{'idfile'}) {
+	    open (A, ">", $self->{'idfile'}) or die ">$self->{'idfile'}";
+	    close A;
+	}
+	$retval = link $self->{'idfile'}, $self->{'pidfile'};
+    }
+    $self->unlock();
+    ::debug("atomic $retval");
+    return $retval;
+}
+
+sub nlinks {
+    my $self = shift;
+    if(-e $self->{'idfile'}) {
+	return (stat(_))[3];
+    } else {
+	return 0;
+    }
+}
+
+sub lock {
+    my ($self) = shift;
+    open $self->{'lockfh'}, ">", $self->{'lockfile'}
+	or die "Can't open semaphore file $self->{'lockfile'}: $!";
+    chmod 0666, $self->{'lockfile'}; # assuming you want it a+rw
+    while(not flock $self->{'lockfh'}, LOCK_EX()|LOCK_NB()) {
+	::debug("Cannot lock $self->{'lockfile'}");
+	# TODO if timeout: last
+	sleep 1;
+    }
+    ::debug("locked $self->{'lockfile'}");
+}
+
+sub unlock {
+    my $self = shift;
+    unlink $self->{'lockfile'};
+    close $self->{'lockfh'};
+    ::debug("unlocked");
+}

unittest/tests-to-run/sem01.sh

@@ -6,10 +6,10 @@ parallel -u --semaphore seq 11 20 '|' pv -qL 100
 parallel --semaphore --wait
 echo done
 
-echo '### Test default id = --id `tty`'
+echo '### Test default id = --id `tty` and --semaphorename'
 parallel --id `tty` -u --semaphore seq 1 10 '|' pv -qL 20
 parallel -u --semaphore seq 11 20 '|' pv -qL 100
-parallel --id `tty` --semaphore --wait
+parallel --semaphorename `tty` --semaphore --wait
 echo done
 
 echo '### Test semaphore 2 jobs running simultaneously'
@@ -30,3 +30,10 @@ for i in 0.5 0.1 0.2 0.3 0.4 ; do
   sem -j+0 sleep $i ";" echo done $i
 done
 sem --wait
+
+echo '### BUG: Test --fg followed by --bg'
+parallel -u --fg --semaphore seq 1 10 '|' pv -qL 20
+parallel -u --bg --semaphore seq 11 20 '|' pv -qL 20
+parallel -u --fg --semaphore seq 21 30 '|' pv -qL 20
+parallel -u --bg --semaphore seq 31 40 '|' pv -qL 20
+sem --wait

unittest/wanted-results/sem01

@@ -20,7 +20,7 @@
 19
 20
 done
-### Test default id = --id `tty`
+### Test default id = --id `tty` and --semaphorename
 1
 2
 3
@@ -61,7 +61,48 @@ done
 done 0.1
 0.3
 done 0.5
-done 0.2
 0.4
+done 0.2
 done 0.3
 done 0.4
+### BUG: Test --fg followed by --bg
+1
+2
+3
+4
+5
+6
+7
+8
+9
+10
+11
+12
+13
+14
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+40