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Интерактивная система просмотра системных руководств (man-ов)

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flock (1)
  • >> flock (1) ( Linux man: Команды и прикладные программы пользовательского уровня )
  • flock (2) ( FreeBSD man: Системные вызовы )
  • flock (2) ( Русские man: Системные вызовы )
  • flock (2) ( Linux man: Системные вызовы )
  • flock (3) ( Solaris man: Библиотечные вызовы )
  • Ключ flock обнаружен в базе ключевых слов.


    flock - Manage locks from shell scripts


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

    flock [-sxun] [-w timeout] fd  


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

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

    The second form is conveninent 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, however, 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 command 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 cannot 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 executing 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 <>.  


    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 PURPOSE.  






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