diff options
| author | Mike Frysinger | 2012-12-26 21:10:29 +0100 |
|---|---|---|
| committer | Karel Zak | 2013-01-09 13:36:58 +0100 |
| commit | 295dd90226852a1f3b3dd108ed01dd1d7da92240 (patch) | |
| tree | dd5a98b5e1afe2079b67680bb744291236a55b3a /sys-utils/flock.1 | |
| parent | include/ttyutils: add default chardata (diff) | |
| download | kernel-qcow2-util-linux-295dd90226852a1f3b3dd108ed01dd1d7da92240.tar.gz kernel-qcow2-util-linux-295dd90226852a1f3b3dd108ed01dd1d7da92240.tar.xz kernel-qcow2-util-linux-295dd90226852a1f3b3dd108ed01dd1d7da92240.zip | |
flock: improve usage strings
The current examples miss the best usage of all: specifying the command
and its arguments directly on the command line. Add that to both the
program usage and the man page.
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Diffstat (limited to 'sys-utils/flock.1')
| -rw-r--r-- | sys-utils/flock.1 | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/sys-utils/flock.1 b/sys-utils/flock.1 index b50c619cf..b28526f69 100644 --- a/sys-utils/flock.1 +++ b/sys-utils/flock.1 @@ -29,10 +29,10 @@ flock \- manage locks from shell scripts .SH SYNOPSIS .B flock -[options] <file> -c <command> +[options] <file|directory> <command> [command args] .br .B flock -[options] <directory> -c <command> +[options] <file|directory> -c <command> .br .B flock [options] <file descriptor number> @@ -120,6 +120,9 @@ shell2> flock -s -w .007 /tmp -c echo; /bin/echo $? Set shared lock to directory /tmp and the second command will not fail. Notice that attempting to get exclusive lock with second command would fail. .TP +shell> flock -x local-lock-file echo 'a b c' +Grab the exclusive lock "local-lock-file" before running echo with 'a b c'. +.TP ( .TQ flock -n 9 || exit 1 @@ -138,6 +141,14 @@ allows the lockfile to be created if it does not already exist, however, write permission is required. Using .I < requires that the file already exists but only read permission is required. +.TP +[ "${FLOCKER}" != "$0" ] && exec env FLOCKER="$0" flock -en "$0" "$0" "$@" || : +This is useful boilerplate code for shell scripts. Put it at the top of the +shell script you want to lock and it'll automatically lock itself on the first +run. If the env var $FLOCKER is not set to the shell script that is being run, +then execute flock and grab an exclusive non-blocking lock (using the script +itself as the lock file) before re-execing itself with the right arguments. It +also sets the FLOCKER env var to the right value so it doesn't run again. .SH "EXIT STATUS" The command uses .B sysexits.h |