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SHLOCK(1)
NAME
  shlock - create lock files for use in shell scripts

SYNOPSIS
  shlock -p pid -f name [ -b ] [ -u ] [ -c ]

DESCRIPTION
  Shlock tries to create a lock file named name and write the process ID pid
  into it.  If the file already exists, shlock will read the process ID from
  the file and test to see if the process is currently running.	 If the
  process exists, then the file will not be created.

  Shlock exits with a zero status if it was able to create the lock file, or
  non-zero if the file refers to currently-active process.

OPTIONS
  -b   Process IDs are normally read and written in ASCII.  If the ``-b''
       flag is used, then they will be written as a binary int.	 For
       compatibility with other systems, the ``-u'' flag is accepted as a
       synonym for ``-b'' since binary locks are used by many UUCP packages.

  -c   If the ``-c'' flag is used, then shlock will not create a lock file,
       but will instead use the file to see if the lock is held by another
       program.	 If the lock is valid, the program will exit with a non-zero
       status; if the lock is not valid (i.e., invoking shlock without the
       flag would have succeeded), then the program will exit with a zero
       status.

EXAMPLES
  The following example shows how shlock would be used within a shell script:
       LOCK=<pathrun in inn.conf>/LOCK.send
       trap 'rm -f ${LOCK} ; exit 1' 1 2 3 15
       if shlock -p $$ -f ${LOCK} ; then
	   # Do appropriate work
       else
	   echo Locked by `cat ${LOCK}`
       fi

BUGS
  shlock does not assumed to be used under a number of lock/unlock
  environment in a short time.	Namely, shlock should be used for an
  environment like daily or hourly based job.

HISTORY
  Written by Rich $alz <rsalz@uunet.uu.net> after a description of HDB UUCP
  locking given by Peter Honeyman.  This is revision 1.5.6.1, dated
  2002/09/24.

SEE ALSO
  inn.conf(5)

Index for Section 1

Alphabetical listing for S

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