NetNews Usenet Archive 1992 #20/NN_1992_20.iso/spool/comp/lang/perl/5768

Internet Message Format | 1992-09-08 | 1.8 KB

Path: sparky!uunet!mcsun!uknet!stl!sbil!wet!spitws117!jim
From: [e-mail] (James Gillespie)
Newsgroups: comp.lang.perl
Subject: Prompting for input
Message-ID: <[e-mail]>
Date: 8 Sep 92 14:16:20 GMT
Sender: [e-mail]
Reply-To: [e-mail]
Organization: Salomon Brothers International Limited
Lines: 40

Yes, it's me again.  Hopefully this problem won't be quite such an own
goal :-)  It is this: I decided to write a little script to execute a
given command on a lot of arguments.  It worked fine.  Then I thought
I'd add a couple of options so that it would say what it was about to
do, and wait for a keyboard input before proceeding.  Then I thought,
"how about a command to skip this occurrence?".  I came up with this
(slightly stripped down):

$command = shift(@ARGV);

 COMMAND:
foreach $file (@ARGV)
{
    print "'$command $file'";
    $ans = getc;
    exit if $ans eq "q";
    next COMMAND if $ans eq "n";

    system $command, $file;
}

This works fine as long as you want to either execute everything or
quit part way through, but if you type "n\n" to skip an instance, it
skips that instance alright but executes the next one without a
pause.  It appears to me that there must be something left on STDIN
as a result of entering the string "n\n", but I can't find anything
in the Camel book about such an occurrence, or how to "suck"
everything off STDIN without sending an EOF.  Setting $| doesn't
appear to have any effect.

Does anybody have any idea what's going on and how to fix it?

Perl version 3.0.1.9, patch level 41

Thanks,

Jim Gillespie ----------------------------------------------------
[e-mail]              Salomon Brothers International Limited
[phone]             ---------------------------------------------------
           "Three strikes and you're history, kiddo!" - Calvin's mom