locks(4)locks(4)NAMElocks - A directory that contains lock files for communication devices
and remote systems that prevent multiple attempts to use the same
device or contact a remote system
SYNOPSIS
/var/spool/locks
DESCRIPTION
Lock files are created by the uucico daemon, the cu command, the tip
command, and the uugetty command in the /var/spool/locks directory. The
files are created when the utility opens the serial line for communica‐
tion.
The lock file locks the device or remote system so that another process
cannot access it while it is in use. The file name of the lock file
uses one of the following forms: LCK..device_name LCK..system_name
Where device_name is the name of the device (such as ttyd0) and sys‐
tem_name is the name of the system (such as hera).
Normally, the process that creates a lock file will remove it when the
process has finished using the line. However, it is possible for lock
files to be left behind (for example: system crash, phone line discon‐
nects unexpectedly). This situation has been accounted for and the com‐
mands that use lock files can handle the situation and overwrite these
files, if appropriate.
Lock files contains the process ID (PID) of the process that created
the lock. The lock file is a data file; to see its contents, use the
following command:
od -d lockfile
Where lockfile is the name of the file. For example: % od -d
/var/spool/locks/LCK..ttyd0 0000000 06854 00000 0000004
In this example, the lock file (LCK..ttyd0) was created by the process
with PID 6854.
FILES
Contains the uucico daemon and uugetty program. Contains the uucp, cu,
and tip programs.
RELATED INFORMATION
Commands: cu(1), od(1), tip(1), uucp(1), uugetty(8)
Daemons: uucico(8) delim off
locks(4)