Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!utgpu!water!watmath!clyde!rutgers!ucla-cs!zen!ucbvax!cartan!brahms.Berkeley.EDU!ballou
From: ballou@brahms.Berkeley.EDU.UUCP
Newsgroups: comp.unix.questions
Subject: Re: executable awk scripts
Message-ID: <1236@cartan.Berkeley.EDU>
Date: Thu, 17-Sep-87 18:40:17 EDT
Article-I.D.: cartan.1236
Posted: Thu Sep 17 18:40:17 1987
Date-Received: Sat, 19-Sep-87 10:12:36 EDT
References: <1881@vax135.UUCP>
Sender: nobody@cartan.Berkeley.EDU
Reply-To: ballou@brahms.Berkeley.EDU.UUCP (Kenneth R. Ballou)
Distribution: na
Organization: Math Dept. UCB
Lines: 39

In article <1881@vax135.UUCP> whb@vax135.UUCP (Wilson H. Bent) writes:
>[ The line-eater lives!  Probably because people keep feeding it...]
>
>Given that these files are executable, why does this fail:
>
>	#!/bin/awk
>	{ print $1 }
>
>when this works:
>
>	#!/bin/sh
>	/bin/awk '{ print $1 }'
>

The semantics of '#!' are as follows.  A command line is constructed by taking
the text immediately following the #! (up to some limit which, I believe, is
30 characters), appending a space, then copying the command line which invoked
the shell script.  So, assuming in both cases the shell script file name is
'foo',  the first case behaves as:

	/bin/awk foo

while the second case behaves as:

	/bin/sh /bin/awk '{ print $1 }'

In the second case, the shell forks a process with command line

	/bin/awk '{ print $1 }'

The first case leaves awk with no program (since a file containing a program
must be specified as -f filename).



--------
Kenneth R. Ballou			ARPA:  ballou@brahms.berkeley.edu
Department of Mathematics		UUCP:  ...!ucbvax!brahms!ballou
University of California