Using grep command to detect presence of script run

Shell Programming and Scripting
1

i have this line of code on a korn shell script to detect the presence of script run:

ISRUNNING=`ps -eaf -o args | grep -i sfs_load_file.ksh | grep -v grep | wc -l`

sometimes this returns either 1, 2, or 3. when it returns 2 or 3 that tells us that there are more than 1 script of sfs_load_file.ksh runs at the same time. when in reality there is none. i suppose that when i run the sfs_load_file.ksh the variable $ISRUNNING should return only 1 that is because there are none other sfs_load_file.ksh is running.

please help and advise. the code might need some tweak or corrections.

thanks so much,
warren

2

You can also fuser the script file, which even detects peopel who source the script ('bash <script' or '. script').

3

Actually it should return 0 if there are 0 processes.
Try this one:

ps -eo args | grep -ic "sfs_load_file[.]ksh"

BTW one can supress the ps header:

ps -eo args= | grep -ic "sfs_load_file[.]ksh"
1 Like
4

Case sensitivity is OK, so 'grep -c' not grep -ic'. The meta characters '[]' escaping the '.' keep it from being counted. LINUX users have 'pgrep -c sfs_load_file.ksh'

Still misses sourced runs, or someone running it through a link or sym-link. The fuser tactic is slower, but gets everyone on the inode. That just leaves people running it through a copy of a different name.

1 Like
5

that works thanks so much

6

Even in pgrep it makes sense to escape the "wildcard dot":

pgrep -c "sfs_load_file[.]ksh"
7

The standard way is to use a PID file. When you run the script, save its PID in a file. That way you can check

if [ -s pidfile ] && ps `cat pidfile` >/dev/null
then
        echo running
else
        echo not running
fi

Much nicer than the ps | awk | sed | cut | kitchen | sink nonsense.

8

pidfiles have their own pitfalls ( pidfalls :smiley: ).
For example, they must be at a volatile location like the /var/run/ that some Unix provide.

9

If the program in question has a directory containing data files it uses, the directory containing those data files might work. In many cases, /tmp is a reasonable place for PIDfiles.