Shell Programming and Scripting

Hello,

I am firing off some scripts from a main script,

Code:

   cd B/
   ./EV_B_m0-m200_hex1.sh &
   ./EV_B_m0-m200_hex2.sh &
   wait
...more

It would be useful to put a bit of time between the two to clean up the output to the terminal.

I think this would work,

Code:

   cd B/
   ./EV_B_m0-m200_hex1.sh &
   sleep 5
   ./EV_B_m0-m200_hex2.sh
...more

but this would not guarantee that the second command would finish before the script continues.

I'm not sure if this would work,

Code:

   cd B/
   ./EV_B_m0-m200_hex1.sh &
   sleep 5
   ./EV_B_m0-m200_hex2.sh &
   wait
...more

As I read it, the first command would execute in a sub-shell and the script would continue and sleep for 5. After that, the third command will execute in a subshell and then the script will wait for both sub-shells to return before it moves on.

Is this right??? Is there a better way to do this kind of thing??

Thanks,

LMHmedchem

When you put a command in background you lose control of exactly when it runs. Meaning no guarantees of order, ever.

If you want some of its output to come first, how about you script it so the bits you want to come first don't run in background?

These scripts don't need to run in any particular order, there output is to files and each script is independent. They just need a bit of time in between when they start, and they both need to finish before the script moves on. The issue is that these two scripts (hex1, hex2) fire off six instances of an application and each instance reports some start up data back to the terminal. Because of the way that they are started, all of that start up data is mixed up and garbled. I am trying to debug a bit and can't read printout to the terminal that I need to look at.

Each script starts three instances of the app and there is a bit of sleep time between each, so if I run just one script, that output is clear. It is only when I run both scripts at the same time that I get this mess. I could not run the second script in the background and wait a bit before starting it, but I need to make sure that both scripts finish before moving on.

If I do what I posted,

Code:

   cd B/
   ./EV_B_m0-m200_hex1.sh &
   sleep 30
   ./EV_B_m0-m200_hex2.sh &
   wait

is this legal syntax? Will this start up hex1, wait for 30, start hex2, and then wait for both hex1 and hex2 to finish before moving on?

LMHmedchem

Yes your syntax is correct and typically hex2 will be run 30 seconds after hex1 was started.

As Corona688 pointed out you are at the mercy of the scheduler and system resources, etc. as to when the jobs will actually be allocated CPU and move into a running state. But since you are only worried about terminal overrun you can safely ignore this, the system would have to be in a pretty bad way for a background job to take any more than a second or two to start.

Well the code above did work and I got clear printout from all six instances of my app. I was able to read the path that couldn't be found and correct the bug.

Thanks for the help!!!

LMHmedchem