Asynchronous shell scripts question - newbie Post: 302482885

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Top Forums Shell Programming and Scripting Asynchronous shell scripts question - newbie Post 302482885 by taskeen21 on Wednesday 22nd of December 2010 10:02:23 PM

12-22-2010

Registered User

Quote:

Originally Posted by purdym

The command you may not know about is:

Code:

wait

.

You already have half the answer. See how wait can help you here.

Thank you. Yea, i came across "wait" through my search. And read about it. Please don't misunderstand me. I am not arguing in any way. I am just trying to understand how this will work exactly so I can convince the interviewer. So, in wait(n) 'n' can be a PID. If i don't specify 'n' the master script will wait for all scripts to finish and return and then continue the execution of further code. So, if i go with this approach how will i know what the PID of "script1 &" and "script2 &" is ?
OR if I go with the "wait", without arguments option, does it mean the script3 will read as simple as this :

<script3's code>
..........
script1 &
script2 &
wait( )
..........
<continue script3's code>

?

---------- Post updated at 06:54 PM ---------- Previous update was at 06:50 PM ----------

Quote:

Originally Posted by migurus

If this needs to be done using Unix shell scripts, then here is a possibility:
- there are three scripts
- scripts #1 and #2 each create a file upon completion, the file will signal OK or FAIL return code of the corresponding script
- script #3 (master) runs both scripts #1 and #2 in the background and waits for the resulting files. I will have a timeout here just in case
- when both files are OK files (meaning scripts #1 and #2 run OK) run the last procedure #3, otherwise say what went wrong
- always cleanup / remove the files from scripts #1 and #2

Just a note: To run a script in the background in unix one has to end the command with '&'

Thank you. That would be a good approach.

---------- Post updated at 07:02 PM ---------- Previous update was at 06:54 PM ----------

Thanks fpmurphy. You are awesome!
I got to know so many things from your sample code. $$ gives calling process' PID and $! gives the called process' PID.
I am sure I could always replace those functions with script file names.
Hats off to you guys. unix.com rocks!

taskeen21

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LEARN ABOUT DEBIAN

gpt-postinstall

GPT-POSTINSTALL(8)					User Contributed Perl Documentation					GPT-POSTINSTALL(8)

NAME

       gpt-postinstall - Searches for post install scripts and executes them

SYNOPSIS

	 gpt-postinstall [-help -force -version -man -location ]

DESCRIPTION

       gpt-postinstall Searches an installation for post-install scripts that have not been run yet and executes them.	These scripts are
       installed by Setup packages and are designed to localize an installation. The -force flag can be used to re-run all of the setup scripts.

OPTIONS

       -force  forces all action to be taken, regardless of state.

       -help   Print a brief help message and exits.

       -man    Prints the manual page and exits.

       -version
	       Prints the version of GPT and exits.

       -location
	       Location indicates the path to the Globus installation that will be used.

SEE ALSO

       gpt-install(1) gpt-uninstall(1) gpt-verify(1)

AUTHOR

       Michael Bletzinger <mbletzin.ncsa.uiuc.edu> and Eric Blau <eblau.ncsa.uiuc.edu>

perl v5.14.2							    2012-04-30							GPT-POSTINSTALL(8)

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