Shell Programming and Scripting

Hi,

In my shell script, (as per the requirement), I am creating few files, and the processes are launched parallelly . (by using "&" at the end of the command line). As per the logic, I need to remove these files as well, after creating.

But, the problem is, due to parallel processing, (while creation) if i am trying to remove the file, then it is not removing, because the previous process is in progress.

For this problem, I need to introduce some piece of code, (something like wait/sleep), which will give more time to complete these process and step for removing files won't be affected.

Ex-

(grep "pattern1" "file1" "file2" ;echo $? >> thread1.txt) &
(grep "pattern2" "file3" "file4" ;echo $? >> thread2.txt) &

------- Few lines of code ---------
rm -f thread1.txt thread2.txt

Hence, in between set of greps, and remove command, I need to use a piece of code, which will give some more time, to execute the grep to execute successfully. (can I use "sleep 1" over here ? or i need to use something else)

Please give some suggestion as this is very urgent for me. Thanks for any kind of help.

Thanks and Regards,

Jitendriya Dash.

You can either let the script wait for the background processes, or sleep for a few seconds, or save the PIDs of the background processes ($!) and check ps -ef if they're still running.

You don't you use "predictive sleep" ? I mean, do you know approximately how long does it takes for the last process to finish ? If you give enough time, like 10 seconds or more, for example - sleep 10, would this be enough ? Then, get the status of the last command with $? and proceed based on the answer.

You can test the output from the shell "jobs" command. When there are no background jobs running it outputs nothing.