Filesystem Hierarchy Standard

5.9 /var/lock : Lock files

5.9.1 Purpose

Lock files should be stored within the /var/lock directory structure.

Lock files for devices and other resources shared by multiple applications, such as the serial device lock files that were originally found in either /usr/spool/locks or /usr/spool/uucp, must now be stored in /var/lock. The naming convention which must be used is "LCK.." followed by the base name of the device. For example, to lock /dev/ttyS0 the file "LCK..ttyS0" would be created.

[footnote 35]

The format used for the contents of such lock files must be the HDB UUCP lock file format. The HDB format is to store the process identifier (PID) as a ten byte ASCII decimal number, with a trailing newline. For example, if process 1230 holds a lock file, it would contain the eleven characters: space, space, space, space, space, space, one, two, three, zero, and newline.

[35] Then, anything wishing to use /dev/ttyS0 can read the lock file and act accordingly (all locks in /var/lock should be world-readable).

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Translated by troff2html v1.5 on 29 March 2002 by Daniel Quinlan