3.5.1 Matrix Server Command Reference

Chapter 1: Matrix Server Commands 45

psfssema – manage matrix-wide file locks

Synopsis

/opt/polyserve/bin/psfssema -i <filename>

/opt/polyserve/bin/psfssema -g <filename>

/opt/polyserve/bin/psfssema -r <filename>

/opt/polyserve/bin/psfssema -d <filename>

Description

The psfssema semaphore utility provides a simple synchronization

mechanism for managing matrix-wide file locks. This utility can be used in

shell scripts on different nodes of a matrix and takes advantage of the PSFS

filesystem and its internode communication abilities. For example, you might

want to use matrix-wide file locking in a Start or Stop script for a service or

device monitor.

The options are:

-i <filename>

Create the PSFS command-line semaphore file <filename> and the

supplemental file <filename.pid> if either file does not already exist. The

command then initializes the files to create the PSFS command-line

semaphore. <filename> must be a path on a PSFS filesystem.

-g <filename>

Lock the PSFS command-line semaphore associated with <filename>,

which is the name of a semaphore file created by psfssema -i. If the

semaphore is already locked by another node in the matrix, the calling

process blocks until the semaphore becomes available.

An error is returned if <filename> does not exist or has not been initialized

by psfssema -i, or if <filename.pid> does not exist.

-r <filename>

Unlock the PSFS command-line semaphore associated with <filename>,

which is the name of a semaphore file created by psfssema -i. If other

nodes are blocked on the semaphore when psfssema-r is called, one of the

blocked psfssema -g processes will return successfully.

-d <filename>

Delete the PSFS command-line semaphore associated with <filename>,

which is the name of a semaphore file created by psfssema -i. It also

deletes <filename> and <filename.pid>.