flock man page on Scientific

Man page or keyword search:  
man Server   26626 pages
apropos Keyword Search (all sections)
Output format
Scientific logo
[printable version]

FLOCK(1)			H. Peter Anvin			      FLOCK(1)

       flock - Manage locks from shell scripts

       flock [-sxon] [-w timeout] lockfile [-c] command...

       flock [-sxon] [-w timeout] lockdir [-c] command...

       flock [-sxun] [-w timeout] fd

       This  utility  manages  flock(2) locks from within shell scripts or the
       command line.

       The first and second forms wraps the lock around the executing  a  com‐
       mand,  in a manner similar to su(1) or newgrp(1).  It locks a specified
       file or directory, which is created (assuming appropriate permissions),
       if it does not already exist.

       The  third form is convenient inside shell scripts, and is usually used
       the following manner:

	 flock -s 200
	 # ... commands executed under lock ...
       ) 200>/var/lock/mylockfile

       The mode used to open the file doesn't matter to flock; using >	or  >>
       allows  the  lockfile  to be created if it does not already exist, how‐
       ever, write permission is required; using  <  requires  that  the  file
       already exists but only read permission is required.

       By  default,  if	 the  lock cannot be immediately acquired, flock waits
       until the lock is available.

       -s, --shared
	      Obtain a shared lock, sometimes called a read lock.

       -x, -e, --exclusive
	      Obtain an exclusive lock, sometimes called a write  lock.	  This
	      is the default.

       -u, --unlock
	      Drop  a  lock.   This  is	 usually not required, since a lock is
	      automatically dropped when the file is closed.  However, it  may
	      be  required  in special cases, for example if the enclosed com‐
	      mand group may have forked a background process which should not
	      be holding the lock.

       -n, --nb, --nonblock
	      Fail  (with an exit code of 1) rather than wait if the lock can‐
	      not be immediately acquired.

       -w, --wait, --timeout seconds
	      Fail (with an exit code of 1) if the  lock  cannot  be  acquired
	      within seconds seconds.  Decimal fractional values are allowed.

       -o, --close
	      Close  the file descriptor on which the lock is held before exe‐
	      cuting command.  This  is	 useful	 if  command  spawns  a	 child
	      process which should not be hold ing the lock.

       -c, --command command
	      Pass a single command to the shell with -c.

       -h, --help
	      Print a help message.

       Written by H. Peter Anvin <hpa@zytor.com>.

       Copyright © 2003-2006 H. Peter Anvin.
       This is free software; see the source for copying conditions.  There is
       NO warranty; not even for MERCHANTABILITY or FITNESS FOR	 A  PARTICULAR


       The flock command is part of the util-linux-ng package and is available
       from ftp://ftp.kernel.org/pub/linux/utils/util-linux-ng/.

flock utility			  4 Feb 2006			      FLOCK(1)

List of man pages available for Scientific

Copyright (c) for man pages and the logo by the respective OS vendor.

For those who want to learn more, the polarhome community provides shell access and support.

[legal] [privacy] [GNU] [policy] [cookies] [netiquette] [sponsors] [FAQ]
Polarhome, production since 1999.
Member of Polarhome portal.
Based on Fawad Halim's script.
Vote for polarhome
Free Shell Accounts :: the biggest list on the net