run-one-constantly(1) - man - phpMan

run-one(1)                                     run-one                                    run-one(1)



NAME
       run-one - run just one instance at a time of some command and unique set of arguments (useful
       for cronjobs, eg)


SYNOPSIS
       run-one COMMAND [ARGS]

       run-this-one COMMAND [ARGS]

       run-one-constantly COMMAND [ARGS]

       keep-one-running COMMAND [ARGS]

       run-one-until-success COMMAND [ARGS]

       run-one-until-failure COMMAND [ARGS]


DESCRIPTION
       run-one is a wrapper script that runs no more than one unique instance of some command with a
       unique set of arguments.

       This is often useful with cronjobs, when you want no more than one copy running at a time.

       run-this-one  is  exactly  like run-one, except that it will use pgrep(1) and kill(1) to find
       and kill any running processes owned by the user and matching the target commands  and  argu‐
       ments.   Note that run-this-one will block while trying to kill matching processes, until all
       matching processes are dead.

       run-one-constantly operates exactly like run-one except that it respawns "COMMAND [ARGS]" any
       time COMMAND exits (zero or non-zero).

       keep-one-running is an alias for run-one-constantly.

       run-one-until-success  operates exactly like run-one-constantly except that it respawns "COM‐
       MAND [ARGS]" until COMMAND exits successfully (ie, exits zero).

       run-one-until-failure operates exactly like run-one-constantly except that it respawns  "COM‐
       MAND [ARGS]" until COMMAND exits with failure (ie, exits non-zero).


EXAMPLE
       In one shell:

        $ run-one rsync -azP $HOME $USER AT example.com:/srv/backup
        foouser/
        foouser/.bash_history
              40298 100%   37.13MB/s    0:00:00 (xfer#1, to-check=3509/3516)
        foouser/.viminfo
              20352 100%   98.39kB/s    0:00:00 (xfer#3, to-check=3478/3516)
        ...
        sent 746228 bytes  received 413059 bytes  36802.76 bytes/sec
        total size is 3732890955  speedup is 3219.99

       In another shell, while the first is still running:

        $ run-one rsync -azP $HOME $USER AT example.com:/srv/backup
        $ echo $?
        1

       Another example...  In one shell:

        $ run-one top

       In another shell:

        $ run-one top
        $ echo $?
        1
        $ run-this-one top
        top - 17:15:36 up  1:43,  3 users,  load average: 1.05, 1.04, 1.00
        Tasks: 170 total,   1 running, 169 sleeping,   0 stopped,   0 zombie
        ...

       And note that the process in the first shell was killed.

       You might want to keep one ssh connection up and running all the time, with:

        $ run-one-constantly ssh -N -C -L 3128:localhost:3128 -L 7778:localhost:7778 example.com &



SEE ALSO
       flock(1), kill(1), pgrep(1)


AUTHOR
       This  manpage and the utility was written by Dustin Kirkland <kirkland AT ubuntu.com> for Ubuntu
       systems (but may be used by others).  Permission is granted to copy, distribute and/or modify
       this  document  under the terms of the GNU General Public License, Version 3 published by the
       Free Software Foundation.

       On Debian systems, the complete text of the GNU  General  Public  License  can  be  found  in
       /usr/share/common-licenses/GPL, or on the web at http://www.gnu.org/licenses/gpl.txt.



run-one                                      9 Jan 2011                                   run-one(1)