halockrun(1M)						  System Administration Commands					     halockrun(1M)

NAME

       halockrun - run a child program while holding a file lock

SYNOPSIS

       /usr/cluster/bin/halockrun [-nsv] [-e exitcode] lockfilename
       prog [args]

DESCRIPTION

       The halockrun utility provides a convenient means to claim a file lock on a file and run a program while holding that lock. As this utility
       supports script locking, this utility is useful when programming in scripting languages such as the Bourne shell. See sh(1).

       halockrun opens the file lockfilename and claims an exclusive mode file lock on the entire file. See fcntl(2) fcntl(2)). Then it  runs  the
       program	prog  with arguments args as a child process and waits for the child process to exit. When the child exits, halockrun releases the
       lock, and exits with the same exit code with which the child exited.

       The overall effect is that the child prog is run as a critical section, and that this critical section is well-formed, in  that	no  matter
       how the child terminates, the lock is released.

       If the file lockfilename cannot be opened or created, then halockrun prints an error message on stderr and exits with exit code 99.

       You  can  run  this command in the global zone or in a non-global zone. The command affects only the global or non-global zone in which you
       issue the command.

OPTIONS

       The following options are supported:

       -e exitcode		   Normally, errors detected by halockrun exit with exit code 99. The -e option provides a means  to  change  this
				   special exit code to a different value.

       -n			   The	lock  should be requested in non-blocking mode: if the lock cannot be granted immediately, halockrun exits
				   immediately, with exit code 1, without running prog. This behavior is not affected by the -e option.

				   Without the -n option, the lock is requested in blocking mode, thus, the halockrun utility blocks  waiting  for
				   the lock to become available.

       -s			   Claim the file lock in shared mode, rather than in exclusive mode.

       -v			   Verbose output, on stderr.

EXIT STATUS

       Errors  detected  by halockrun itself, such that the child process was never started, cause halockrun to exit with exit code 99. (This exit
       code value can be changed to a different value using the -e option. See OPTIONS.

       Otherwise, halockrun exits with the same exit code with which the child exited.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWscu			   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Evolving			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       fcntl(2), attributes(5)

Sun Cluster 3.2 						    10 Apr 2006 						     halockrun(1M)