Path: utzoo!utgpu!water!watmath!clyde!cbosgd!ihnp4!homxb!mhuxt!mhuxm!mhuxo!ulysses!allegra!mit-eddie!husc6!think!ames!aurora!labrea!decwrl!decvax!ima!minya!jc
From: jc@minya.UUCP
Newsgroups: comp.unix.questions
Subject: Re: Using pipes within awk programs
Summary: nor on Sys/V.2
Keywords: awk, pipe
Message-ID: <455@minya.UUCP>
Date: 23 Jan 88 16:41:02 GMT
References: <515@root44.co.uk> <2138@geac.UUCP>
Organization: home
Lines: 37

In article <2138@geac.UUCP>, ivor@geac.UUCP (Ivor Williams) writes:
> In article <515@root44.co.uk> you write:
> >	who | awk '{ print $1 | "sort" }'
> >gives the same output as
> >	who | awk '{ print $1 }' | sort
> 
> FYI, the two *don't* give the same results under Ultrix T2.0-1I.

Nor on this Sys/V machine, and I am rather mystified at the difference.
The second produces output like I expect.  My prompt is set up to show
the current directory, so what I see on my screen when I use the second
command is:
| 	/usr/jc: who | awk '{ print $1 }' | sort
| 	jc
| 	std
| 	/usr/jc:

However, when I try the first command, the screen looks like:
|	/usr/jc: who | awk '{ print $1 | "sort" }'
|	/usr/jc: jc
|	std

In other words, I get a new shell prompt, and THEN I get the output
from the command.  There was no '&' anywhere in the line.  Does anyone
have an explanation as to why the output was delayed like this?  It
looks like awk is starting the sub-process and exiting without waiting
for it to complete.  I find this a bit surprising, not to mention a
bit weird.  Consider also:

|	/usr/jc: who | awk '{ print $1 | "sort" }' |wc
|      2      2      7

This appears to work correctly, so I clearly don't understand what's
going on here.

-- 
John Chambers <{adelie,ima,maynard,mit-eddie}!minya!{jc,root}> (617/484-6393)