How about using map. 
use strict;

open(INFILE, "/path/to/file");
my @lines = map {s/oldthing/newthing/ if(m/myLine/);$_;} <INFILE>;
close(INFILE);

open(OUTFILE, ">/path/to/file");
print OUTFILE $_ foreach(@lines);
close(OUTFILE);

[download]

UPDATE: Changed print to filehandle(OUTFILE) instead of STDOUT

In reply to Re: Use of grep and foreach by tcf22
in thread Use of grep and foreach by monaLisa

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