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Full Discussion: Processing a file list via named pipe
Top Forums Shell Programming and Scripting Processing a file list via named pipe Post 302808773 by benalt on Friday 17th of May 2013 01:13:04 PM
Old 05-17-2013
Processing a file list via named pipe
I have a ksh93 script I use that processes a file list in the order that they exist in the list. I would like to speed up processing of the list by having multiple processes handle it at once. I was thinking that perhaps a good way to handle this would be to write the list to a named pipe and some number of processes that I can specify would be created and read from the named pipe the file it could work on and when finished with that file it would again read the named pipe until nothing is left. Each process would read the named pipe after finishing processing a file. The files then would be processed close to the order they existed in the file list which I need done.

My only consideration is regarding how to stop the processes from then hanging waiting for more input from the named pipe when there are no more files left to process. Would the best way to handle that be to write several times some kind of exit flag to the named pipe so that the processes as they read the next file from the list will instead encounter the exit flag and know to exit or is there a better way?
 

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LEARN ABOUT X11R4

times

times(1)							   User Commands							  times(1)

NAME

       times - shell built-in function to report time usages of the current shell

SYNOPSIS

   sh
       times

   ksh
       times

DESCRIPTION

   sh
       Print the accumulated user and system times for processes run from the shell.

   ksh
       Print the accumulated user and system times for the shell and for processes run from the shell.

       On this man page, ksh(1) commands that are preceded by one or two * (asterisks) are treated specially in the following ways:

       1.  Variable assignment lists preceding the command remain in effect when the command completes.

       2.  I/O redirections are processed after variable assignments.

       3.  Errors cause a script that contains them to abort.

       4.  Words,  following a command preceded by ** that are in the format of a variable assignment, are expanded with the same rules as a vari-
	   able assignment. This means that tilde substitution is performed after the = sign and word splitting and file name generation  are  not
	   performed.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWcsu			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       ksh(1), sh(1), time(1), attributes(5)

SunOS 5.10							    15 Apr 1994 							  times(1)
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