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Full Discussion: How can a file be locked for a certain time?
Top Forums UNIX for Dummies Questions & Answers How can a file be locked for a certain time? Post 11676 by rwb1959 on Monday 10th of December 2001 03:06:33 PM
Old 12-10-2001
A "lock" file is nothing more than an ordinary file
that is used a a sort of "semaphore". Meaning, for example,
you can create a lock file from within a shell script
(say "myprog.ksh")
that can contain the shell script's process ID by doing...

echo $$ > /tmp/myprog..LCK

...this will create the file called "myprog..LCK" in the
"/tmp" directory. This file will contain the process id of
the shell script "myprog.ksh" for that particular instance
in which it was run.

There are several good reasons to do this. For instance,
"myprog.ksh" may be executed every 60min via "cron" but
occasionally make take more than 60min to complete. Therefore
you may wish to skip execution if the previous execution
is still running.

However, I'm not exactly clear on your requirements. It may
be that a lock file is not necessary. For example, if you wanted to
execute a shell script every 60min you could simply create a
"cron" job to run at 60min intervals.
 

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LEARN ABOUT OPENSOLARIS

suspend

suspend(1)							   User Commands							suspend(1)

NAME

       suspend - shell built-in function to halt the current shell

SYNOPSIS

   sh
       suspend

   csh
       suspend

   ksh
       suspend

DESCRIPTION

   sh
       Stops the execution of the current shell (but not if it is the login shell).

   csh
       Stop the shell in its tracks, much as if it had been sent a stop signal with ^Z. This is most often used to stop shells started by su.

   ksh
       Stops the execution of the current shell (but not if it is the login shell).

ATTRIBUTES

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

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWcsu			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       csh(1), kill(1), ksh(1), sh(1), su(1M), attributes(5)

SunOS 5.11							    15 Apr 1994 							suspend(1)
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