Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!elroy.jpl.nasa.gov!jpl-devvax!lwall
From: lwall@jpl-devvax.jpl.nasa.gov (Larry Wall)
Newsgroups: comp.lang.perl
Subject: Re: Intercepting the Mail output with a Perl program
Message-ID: <1991May8.172447.28951@jpl-devvax.jpl.nasa.gov>
Date: 8 May 91 17:24:47 GMT
References: <6819@s3.ireq.hydro.qc.ca>
Reply-To: lwall@jpl-devvax.JPL.NASA.GOV (Larry Wall)
Organization: Jet Propulsion Laboratory, Pasadena, CA
Lines: 36

In article <6819@s3.ireq.hydro.qc.ca> regie@ireq-robot.hydro.qc.ca (Regis Houde) writes:
: 
: I wrote a program that intercepts the output of the standard
: /usr/ucb/Mail program in order to interpret and replace a set of
: characters. I'd like the program to behave exactly like the original
: one so a program calling it (as mailtool) won't make any difference.
: 
: Here is my program :
: 
: #!/usr/bin/perl
: # Name : Mail
: # Usage : Mail
: 
:    # Make the stdio unbuffered
:    select((select(stdout), $| = 1)[0]);
:    select((select(stdin), $| = 1)[0]);
: 
:    open(IN,"/usr/ucb/mail @ARGV |");
: 
:    while(<IN>)
:    {
: # Some simple code here
:      print ;
:    }
: 
: It does pretty well except for the prompt that doesn't come at the
: right time and this seems to bug mailtool when a user press the delete
: button. 

I don't know if it's the whole story, but <IN> does line-oriented input,
so any prompt not ending in newline is going to languish in the STDIN
buffer until a newline comes along.  Setting $| on STDIN has no effect.
Replace the <IN> with sysread(STDIN,$_,1024) or read(STDIN,$_,1) and it
should be closer to the truth.

Larry