Re: general perl question

[repson]

in reply to In-place editing of files (was: general perl question)

If your program is not being run on the command line you could use code similar to this.

my $filename = 'foo.txt';

open IN, "< $filename" or die "Can't open $filename: $!\n";
open OUT, "> $filename.bak" or die "Can't write to $filename: $!\n";
while (<IN>) {
  s/foo/blah/g;
  print OUT $_;
}
close IN; close OUT;
rename "$filename.bak", $filename;

However this code is only the barest code that will work, and should probably not be used without file locks and other sanity checks.

[petdance]

The flags work without the command line, too. The following will convert any files specified on the command line to all caps.

#!/usr/bin/perl -w -i.bak -p

$_ = uc;

In fact, there was an Obfuscated Perl contest entry a while back that does DOS-to-Unix conversions using only command line switches on the shebang line.

xoxo,
Andy

# Andy Lester  http://www.petdance.com  AIM:petdance
%_=split';','.; Perl ;@;st a;m;ker;p;not;o;hac;t;her;y;ju';
print map $_{$_}, split //,
'[e-mail]'

[repson]

What I meant was that my code can be dropped in the middle of a program, while to use the switches in the middle of a program you would have to spawn a new perl with those switches.

#!/usr/bin/perl -w
.....
system(q#perl -i.bak -p -e '$_ = uc'#);
.....