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Taylor UUCP

4.4.5 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 section 5.6.1 Miscellaneous config File Commands).

For a description of the names used for device lock files, and the format of the contents of a lock file, see 6.3 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 (see section 5.6.1 Miscellaneous config File Commands). It is also used to parcel out the `.Xqtdir' subdirectories (see section 4.4.3 Execution Subdirectories).

`LXQ.cmd'

When uuxqt is invoked with the `-c' or `--command' option (see section 2.11 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 section 4.4.1 System Spool Directories). It is only used on systems which do not support POSIX file locking using the fcntl system call.