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lockf (1)
  • >> lockf (1) ( FreeBSD man: Команды и прикладные программы пользовательского уровня )
  • lockf (3) ( Solaris man: Библиотечные вызовы )
  • lockf (3) ( FreeBSD man: Библиотечные вызовы )
  • lockf (3) ( Русские man: Библиотечные вызовы )
  • lockf (3) ( Linux man: Библиотечные вызовы )
  • lockf (3) ( POSIX man: Библиотечные вызовы )

  • BSD mandoc
     

    NAME

    lockf
    
     - execute a command while holding a file lock
    
     
    

    SYNOPSIS

    [-ks ] [-t seconds ] file command [arguments ]  

    DESCRIPTION

    The utility acquires an exclusive lock on a file creating it if necessary, Bf Em and removing the file on exit unless explicitly told not to. Ef While holding the lock, it executes a command with optional arguments After the command completes, releases the lock, and removes the file unless the -k option is specified. BSD -style locking is used, as described in flock(2); the mere existence of the file is not considered to constitute a lock.

    If the utility is being used to facilitate concurrency between a number of processes, it is recommended that the -k option be used. This will guarantee lock ordering, as well as implement a performance enhanced algorithm which minimizes CPU load associated with concurrent unlink, drop and re-acquire activity. It should be noted that if the -k option is not used, then no guarantees around lock ordering can be made.

    The following options are supported:

    -k
    Causes the lock file to be kept (not removed) after the command completes.
    -s
    Causes to operate silently. Failure to acquire the lock is indicated only in the exit status.
    -t seconds
    Specifies a timeout for waiting for the lock. By default, waits indefinitely to acquire the lock. If a timeout is specified with this option, will wait at most the given number of seconds before giving up. A timeout of 0 may be given, in which case will fail unless it can acquire the lock immediately. When a lock times out, command is not executed.

    In no event will break a lock that is held by another process.  

    EXIT STATUS

    If successfully acquires the lock, it returns the exit status produced by command Otherwise, it returns one of the exit codes defined in sysexits(3), as follows:

    EX_TEMPFAIL
    The specified lock file was already locked by another process.
    EX_CANTCREAT
    The utility was unable to create the lock file, e.g., because of insufficient access privileges.
    EX_USAGE
    There was an error on the command line.
    EX_OSERR
    A system call (e.g., fork(2)) failed unexpectedly.
    EX_SOFTWARE
    The command did not exit normally, but may have been signaled or stopped.

     

    SEE ALSO

    flock(2), sysexits(3)  

    HISTORY

    A utility first appeared in Fx 2.2 .  

    AUTHORS

    An John Polstra Aq [email protected]


     

    Index

    NAME
    SYNOPSIS
    DESCRIPTION
    EXIT STATUS
    SEE ALSO
    HISTORY
    AUTHORS


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