Lock Files in the Spool Directory
---------------------------------

   Lock files for devices and systems are stored in the lock directory,
which may or may not be the same as the spool directory.  The lock
directory is set at compilation time by `LOCKDIR' in `policy.h', which
may be overridden by the `lockdir' command in the `config' file (
see Miscellaneous (config).).

   For a description of the names used for device lock files, and the
format of the contents of a lock file, see See UUCP Lock Files.

`LCK..SYS'
     A lock file for a system, where SYS is the system name.  As noted
     above, these lock files are kept in the lock directory, which may
     not be the spool directory.  These lock files are created by
     `uucico' while talking to a remote system, and are used to prevent
     multiple simultaneous conversations with a system.

     On systems which limit file names to 14 characters, only the first
     eight characters of the system name are used in the lock file
     name.  This requires that the names of each directly connected
     remote system be unique in the first eight characters.

`LCK.XQT.NN'
     When `uuxqt' starts up, it uses lock files to determine how many
     other `uuxqt' daemons are currently running.  It first tries to
     lock `LCK.XQT.0', then `LCK.XQT.1', and so forth.  This is used to
     implement the `max-uuxqts' command (*note Miscellaneous
     (config)::.).  It is also used to parcel out the `.Xqtdir'
     subdirectories (see Execution Subdirectories.).

`LXQ.CMD'
     When `uuxqt' is invoked with the `-c' or `--command' option (
see Invoking uuxqt.), it creates a lock file named after the command
     it is executing.  For example, `uuxqt -c rmail' will create the
     lock file `LXQ.rmail'.  This prevents other `uuxqt' daemons from
     executing jobs of the specified type.

`SYSTEM/X./L.XXX'
     While `uuxqt' is executing a particular job, it creates a lock file
     with the same name as the `X.' file describing the job, but
     replacing the initial `X' with `L'.  This ensures that if multiple
     `uuxqt' daemons are running, they do not simultaneously execute
     the same job.

`LCK..SEQ'
     This lock file is used to control access to the sequence files for
     each system (see System Spool Directories.).  It is only used
     on systems which do not support POSIX file locking using the
     `fcntl' system call.