Check whether shell script has started.

Shell Programming and Scripting
1

How can i ceck as shellscript, if a other shellscript has been started?

The other script can bee started by a other user.
The task will not run twice

2

You could have the script create a lockfile. It will need some way to determine if it's been run before.

3

If executed in a subshell, ps will show it as a parameter to your shell, so you can check. What do you mean by "twice"? Two instances in parallel, twice during an hour, a day, a week?

4

Since a shellscript has access to it's PID through $$, one could do something like

#!/bin/sh                                                                      

echo my pid $$
echo my name $0
if ( ps -ef | grep -v grep |grep "/bin/sh $0" | grep -v $$ ) ; then
   echo somebody else is running  $$ cancelling
   exit
fi

echo me running, continuing with execution

while (true) ; do
  continue
done
<continue with script>

The test in the if statment has the "added?" benefit of returning which processes are interfering with your own instance.

But that's today's brain-teaser for me. :slight_smile:

[later] forgot demonstration:

$ ./try.sh &
[2] 10191
my pid 10191
my name ./try.sh
me running, continuing with execution

$ ./try.sh
my pid 17374
my name ./try.sh
<username>   10191 26900 30 12:56 pts/2    00:00:01 /bin/sh ./try.sh
somebody else is running 17374 cancelling
5

Since each call of a new script, specialy if by another user, gets another pid, this method is not very reliable.

Instread i'd check:

script_name=try.sh
ps -ha | grep "$script_name" | grep -v grep

hth

6

ps -ha | grep [t]ry.sh

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