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From: mek@michael.udev.cdc.com (Mark Kennedy)
Newsgroups: comp.unix.programmer,comp.unix.misc
Subject: Re: Awk
Message-ID: <31137@shamash.cdc.com>
Date: 7 Mar 91 19:32:11 GMT
References: <1991Mar7.115420.21315@daimi.aau.dk>
Sender: usenet@shamash.cdc.com
Reply-To: mek@michael.udev.cdc.com (Mark Kennedy)
Followup-To: comp.unix.programmer
Organization: Control Data Corporation
Lines: 44

In article <1991Mar7.115420.21315@daimi.aau.dk>, ezra@daimi.aau.dk (Thomas Ravnholt) writes:
|> Hello !
|> 
|>   I have a little question about awk (nawk).
|> 
|>   If I want to run a unix-command in an awk-script,
|> how do I get the output into a variable.
|> 
|>   I tried
|> 
|>      getline < system(unixcommand)
|> 
|>      system(unixcommand | getline)
|> 
|> 
|> but it is no good of course. system returns 0 or 1 and
|> not the output of the unixcommand.
|> 

Crude, but effective, temporary files are your friend.  Here's a
simple example that does what you ask.

#! /bin/sh

awk '
BEGIN {
system("date > /tmp/foo")
getline X < "/tmp/foo"
print X
}'

You can use the pid if you are worried about stepping on duplicate
temp file names and insert a "trap" command to delete your temp
file(s) in case your script terminates prematurely.

     -Mark


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