#!/usr/bin/perl -w
use strict;

open (INPUT, "original") or die "Unable to open input file : $!";

open (OUTPUT, ">newfile") or die "Unable to open output file : $!";
select OUTPUT;

my ($match, $replaced);
while (<INPUT>) {
    $match = 1 if $_ =~ /baz/;
    if ($match && ! $replaced) {
        print "Replacement Line\n$_";
        ($match, $replaced) = (0, 1);
    }
    else {
        print;
    }
}
[download]

Cheers - L~R

Excellent! That did it.

Glenn

perl -pi.bak -e" /\(baz-\d+\)/ and print 'bar=2'.$/" file
[download]

Okay -- but one needs to be careful about those quotes on the command line. In bash (or any bourne-like shell, whether on *nix or wintel), having the double-quotes on the outside (around the script) means that strings in the script that begin with "$" could be interpolated by the shell as environment variables (which might yield empty strings).

The problem doesn't apply in this particular case, because shell variable names have to start with an alphanumeric ("$1" etc are shell variables); as a general rule, bourne-shell users habituate toward single quotes around perl one-liners on the command line. (I suppose with "command.com", the behavior may be different.) (update: for those, like Browser UK, who didn't know, "command.com" is the DOS/Windows executable that is the standard DOS command-line interface)

What's command.com?

---

Examine what is said, not who speaks.
"Efficiency is intelligent laziness." -David Dunham
"When I'm working on a problem, I never think about beauty. I think only how to solve the problem. But when I have finished, if the solution is not beautiful, I know it is wrong." -Richard Buckminster Fuller
If I understand your problem, I can solve it! Of course, the same can be said for you.

See also perldoc -q "insert a line" (or search for the same in perldoc perlfaq5).

--

flounder

perl -pe"if($_eq'baz-123'){print'bar=2'}" old_file.txt > new_file.txt
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uh..

C:\>perl -pe"if($_eq'baz-123'){print'bar=2'}" old > new
String found where operator expected at -e line 1, near "123'){print'"
        (Missing operator before '){print'?)
Bareword found where operator expected at -e line 1, near "'){print'ba
+r"
        (Missing operator before bar?)
String found where operator expected at -e line 1, at end of line
        (Missing semicolon on previous line?)
syntax error at -e line 1, near "123'){print'"
Can't find string terminator "'" anywhere before EOF at -e line 1.
[download]

Why not use the -i command line option?
Since baz is the only constant, it should be =~ /baz/ and not eq
print 'bar=2' wtf is the newline?
Thanks for broken code that would not do the job even if it worked

So he forgot a space in $_hereeq, and he doesn't print a single newline, big f-ing deal (no need to be rude).