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Full Discussion: Background processes
Top Forums UNIX for Advanced & Expert Users Background processes Post 7188 by Perderabo on Thursday 20th of September 2001 09:56:56 AM
Old 09-20-2001
In ksh at least this is easy. First when you background a job, save the value of $! which will be the pid of the background job. The background job will eventally finish and become a zombie. It will stay a zomblie until the parent waits for it and retrieves the exit code. In ksh, this is done with the "wait" command. The exit code of the wait command will be the exit code of the process that was waited for. This sounds complex but try this script:
Code:
#! /usr/bin/ksh
true &
pid=$!
wait $pid
rc=$?
echo rc = $rc

false &
pid=$!
wait $pid
rc=$?
echo rc = $rc

exit 0

However, in your sample, I don't see why you bothered to background the job, since the next step is to ask if it worked. Why not just leave it in the foreground? Well, maybe it was just an over-simplified example much like my own sample code.
 

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WAIT(1) 						    BSD General Commands Manual 						   WAIT(1)

NAME
wait -- await process completion SYNOPSIS
wait [pid] DESCRIPTION
If invoked with no arguments, the wait utility waits until all existing child processes in the background have terminated. Available operands: pid If a pid operand is specified, and it is the process ID of a background child process that still exists, the wait utility waits until that process has completed and consumes its status information, without consuming the status information of any other process. If a pid operand is specified that is not the process ID of a child background process that still exists, wait exits without waiting for any processes to complete. The wait utility exits with one of the following values: 0 The wait utility was invoked with no operands and all of the existing background child processes have terminated, or the process specified by the pid operand exited normally with 0 as its exit status. >0 The specified process did not exist and its exit status information was not available, or the specified process existed or its exit status information was available, and it terminated with a non-zero exit status. If the specified process terminated abnormally due to the receipt of a signal, the exit status information of wait contains that termination status as well. STANDARDS
The wait command is expected to be IEEE Std 1003.2 (``POSIX.2'') compatible. BSD
June 5, 1993 BSD
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