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Top Forums UNIX for Dummies Questions & Answers How do you wait for command substitution processes to complete? Post 302398060 by methyl on Tuesday 23rd of February 2010 07:01:50 PM
Old 02-23-2010
Like "drl" I don't get exactly what you are tying to achieve. I can't see why there is the complexity of redirecting channels.

It seems that you want to issue multiple command sets concurrently and wait until they have all completed.

IMHO forget using exec. It will drive you nuts with multiple concurrent processes.

Best approach is to background the command (or lots of commands).
[CODE]nohup command_name &[/CODE

Then check for background jobs.
Code:
jobs

When there are no background jobs running, all the background jobs for your user have completed.

I'll leave you to script processing the output (or not!) from the shell command "jobs". See "man" for your shell to read about "jobs".
 

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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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