No lock file: Preventing multiple instance of a script
I've been bitten by using a lock or pid file to prevent multiple instances of a script. A user typed kill -9, and the pid file didn't go away. You can't trap -9. So when he tried to restart, it said "already running", and I got trouble report. Argh.
So here's what we came up with:
It does use a temp file, but leaves no potential artifact to mess us up later.
If you try this without a temp file, you'll end up with a false positive because pids=$(ps | grep $0 | grep -v grep | cut -d ' ' -f 1) seems to leave it's own extra pid.
Last edited by Scott; 11-17-2011 at 09:43 PM..
Reason: Please use code tags
;)Hi Everyone,
I am using solaris 5.10.
I have a java process running in server mode in unix.
The problem is that it automatically forks i.e creates a child process.
I mean suddenly two instances of that process start running , in which the process-id of first instance is the parent... (0 Replies)
Hi Everyone,
I am using solaris 5.10.
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The problem is that it automatically forks i.e creates a child process.
I mean suddenly two instances of that process start running , in which the process-id of first instance is the parent... (5 Replies)
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I have a problem mentioned below.
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Hi all,I have some questions of forking new process,the code is below.Any help will be appreciated.
1 #! /bin/bash
2
3 PIDS=$(pidof sh $0)
4 P_array=( $PIDS )
5 echo $PIDS
6 let "instances = ${#P_array}-1"
7
8 echo "$instances instance(s)" of this script running."
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Hi all,
i have a small script to remove locks for the prevous day and create new lock for processing in the path on my server
i have made something like this
#!/bin/sh
#lock_remover
#script to remove regular lockfiles and hang
curr_month=`date "+%b"`
2day=`date "+%_d"`
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Hi all,
i have compiled a script as below. Basically this script is intended to call 3 other scripts, which i intend to run simultaneously.
#!/usr/bin/bash
HOMEDIR=/path/of/home
LOCKDIR=$HOMEDIR/lock
#check for LOCK
LOCKFILE=$LOCKDIR/$(basename $0 .sh).lock
if ; then
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Discussion started by: nms
2 Replies
LEARN ABOUT LINUX
lockfile-remove
lockfile-progs(1) Lockfile programs lockfile-progs(1)NAME
lockfile-progs - command-line programs to safely lock and unlock files and mailboxes (via liblockfile).
SYNOPSIS
mail-lock [--use-pid] [--retry retry-count]
mail-unlock
mail-touchlock [--oneshot]
lockfile-create [--use-pid] [--retry retry-count] [--lock-name] filename
lockfile-remove [--lock-name] filename
lockfile-touch [--oneshot] [--lock-name] filename
lockfile-check [--use-pid] [--lock-name] filename
DESCRIPTION
Lockfile-progs provides a set a programs that can be used to lock and unlock mailboxes and files safely (via liblockfile):
mail-lock - lock the current user's mailbox
mail-unlock - unlock the current user's mailbox
mail-touchlock - touch the lock on the current user's mailbox
lockfile-create - lock a given file
lockfile-remove - remove the lock on a given file
lockfile-touch - touch the lock on a given file
lockfile-check - check the lock on a given file
By default, the filename argument refers to the name of the file to be locked, and the name of the lockfile will be filename .lock. How-
ever, if the --lock-name argument is specified, then filename will be taken as the name of the lockfile itself.
Each of the mail locking commands attempts to lock /var/spool/mail/<user>, where <user> is the name associated with the effective user ID,
as determined by via geteuid(2).
Once a file is locked, the lock must be touched at least once every five minutes or the lock will be considered stale, and subsequent lock
attempts will succeed. Also see the --use-pid option and the lockfile_create(3) manpage.
The lockfile-check command tests whether or not a valid lock already exists.
OPTIONS -q, --quiet
Suppress any output. Success or failure will only be indicated by the exit status.
-v, --verbose
Enable diagnostic output.
-l, --lock-name
Do not append .lock to the filename. This option applies to lockfile-create, lockfile-remove, lockfile-touch, or lockfile-check.
-p, --use-pid
Write the current process id (PID) to the lockfile whenever a lockfile is created, and use that pid when checking a lock's validity.
See the lockfile_create(3) manpage for more information. This option applies to lockfile-create, lockfile-remove, lockfile-touch, and
lockfile-check.
-o, --oneshot
Touch the lock and exit immediately. This option applies to lockfile-touch and mail-touchlock. When not provided, these commands will
run forever, touching the lock once every minute until killed.
-r retry-count, --retry retry-count
Try to lock filename retry-count times before giving up. Each attempt will be delayed a bit longer than the last (in 5 second incre-
ments) until reaching a maximum delay of one minute between retries. If retry-count is unspecified, the default is 9 which will give
up after 180 seconds (3 minutes) if all 9 lock attempts fail.
EXAMPLES
Locking a file during a lengthy process:
lockfile-create /some/file
lockfile-touch /some/file &
# Save the PID of the lockfile-touch process
BADGER="$!"
do-something-important-with /some/file
kill "${BADGER}"
lockfile-remove /some/file
EXIT STATUS
0
For lockfile-check this indicates that a valid lock exists, otherwise it just indicates successful program execution.
Not 0
For lockfile-check a non-zero exit status indicates that the specified lock does not exist or is not valid. For other programs it
indicates that some problem was encountered.
SEE ALSO maillock(3)touchlock(3)mailunlock(3)lockfile_create(3)lockfile_remove(3)lockfile_touch(3)lockfile_check(3)AUTHOR
Written by Rob Browning <rlb@defaultvalue.org>
0.1.12 2008-02-10 lockfile-progs(1)