Shell Programming and Scripting

Hi,

I have on shell script which internally calls more than one scripts which run in background.
These scripts cannot be modified to run in foreground.

eg. myscript.sh -> bulk_launcher.sh -> acq_launcher.sh
-> bulk_loader.sh

I want the calling shell script myscript.sh to wait till the other finish their successful execution.

So that after this I can trigger another job.

How do I do this?

Thanks.

general approach to this problem is:

Code:

script1  2&>1 > log1 &  
script2  2&>1 > log2 &  
script3  2&>1 > log3 &  
wait   # this will wait until script1 script2 and script3 are finished

Is that what you mean?

Standard interview question, and actually, many variations on the answer. First, classic wait for specific job:

Code:

set -o bgnice off   # ksh thinks bg jobs are second class
Job_1&
pid_job_1=$!
Job_2&
pid_job_2=$!
 .
 .
 .
wait $pid_job_1
 .
 .
 .
wait $pid_job_2

You can also wait for all jobs with a barefoot wait. Check man ksh. When running a bare wait from the command line, be aware that it waits for other, unrelated jobs you ran from that terminal shell.

Also beware, the child processes will be done, but their descendents may still be running!

More sophisticated, and capable of monitoring all descendent processes:

Code:

(
job1 &
job2 &
) 2>&1 | cat -u >>$jobs_log

When every process inside the parentheses closes (or redirects) both stdout and stderr, the cat will end. You can use stdout for payload or logging, but generally, to keep the parent waiting, reserve one of the two for logging. Plus, you have an integrated log, always a nice idea.

You can also run fuser on the log files to see if any pid has it open. Of course, if someone has their vi nose in there, you will think it is still being written unless you check the pids with ps -fp $pid.

Further to DGPickett.

You can check what jobs are still running with the Shell "jobs" command.

Re: jobs: Only if it is interactive -- no shell script can do this unless it has an expect layer or other source of tty. Even then, you get jobs of other tasks also in the background on this tty, like with wait. Just from memory, I think running on the command line in a subshell ( ; wait) allows you to avoid waiting for unrelated processes.

I like my servers to work unattended!

This is not true. Try it.

You are right. This allows you to test without blocking, too. Like wait on the command line, you get all the background. If you subshell or are scripting, you are free of them -- Other People's Children OPC. Of course, their children may still be running! The inheritied stdout/err (...)| cat can track the deeper children.

Code:

$ sleep 99&
[1]     21207
$ sleep 98 &
[2]     21211
$ jobs
[2] +  Running                 sleep 98 &
[1] -  Running                 sleep 99&
$ (sleep 97 & jobs)
[1]     21220
[1] +  Running                 (sleep 97 & jobs)
$

---------- Post updated at 02:25 PM ---------- Previous update was at 02:25 PM ----------

PS: Unlike jobs, fg does not make the batch trip.