Is there a simple way to do bulk file text substitution in place?

Asked 2008-10-29T22:29:02.987

I've been trying to code a Perl script to substitute some text on all source files of my project. I'm in need of something like:

perl -p -i.bak -e "s/thisgoesout/thisgoesin/gi" *.{cs,aspx,ascx}

But that parses all the files of a directory recursively.

I just started a script:

use File::Find::Rule;
use strict;

my @files = (File::Find::Rule->file()->name('*.cs','*.aspx','*.ascx')->in('.'));

foreach my $f (@files){
    if ($f =~ s/thisgoesout/thisgoesin/gi) {
           # In-place file editing, or something like that
    }
}

But now I'm stuck. Is there a simple way to edit all files in place using Perl?

Please note that I don't need to keep a copy of every modified file; I'm have 'em all subversioned =)

Update: I tried this on Cygwin,

perl -p -i.bak -e "s/thisgoesout/thisgoesin/gi" {*,*/*,*/*/*}.{cs,aspx,ascx

But it looks like my arguments list exploded to the maximum size allowed. In fact, I'm getting very strange errors on Cygwin...

Edit Report

2 Answers

You may be interested in File::Transaction::Atomic or File::Transaction

The SYNOPSIS for F::T::A looks very similar with what you're trying to do:

  # In this example, we wish to replace 
  # the word 'foo' with the word 'bar' in several files, 
  # with no risk of ending up with the replacement done 
  # in some files but not in others.

  use File::Transaction::Atomic;

  my $ft = File::Transaction::Atomic->new;

  eval {
      foreach my $file (@list_of_file_names) {
          $ft->linewise_rewrite($file, sub {
               s#\bfoo\b#bar#g;
          });
      }
  };

  if ($@) {
      $ft->revert;
      die "update aborted: $@";
  }
  else {
      $ft->commit;
  }

Couple that with the File::Find you've already written, and you should be good to go.

answered 2008-10-29T23:19:24.273

Change

foreach my $f (@files){
    if ($f =~ s/thisgoesout/thisgoesin/gi) {
           #inplace file editing, or something like that
    }
}

foreach my $f (@files){
    open my $in, '<', $f;
    open my $out, '>', "$f.out";
    while (my $line = <$in>){
        chomp $line;
        $line =~ s/thisgoesout/thisgoesin/gi
        print $out "$line\n";
    }
}

This assumes that the pattern doesn't span multiple lines. If the pattern might span lines, you'll need to slurp in the file contents. ("slurp" is a pretty common Perl term).

The chomp isn't actually necessary, I've just been bitten by lines that weren't chomped one too many times (if you drop the chomp, change print $out "$line\n"; to print $out $line;).

Likewise, you can change open my $out, '>', "$f.out"; to open my $out, '>', undef; to open a temporary file and then copy that file back over the original when the substitution's done. In fact, and especially if you slurp in the whole file, you can simply make the substitution in memory and then write over the original file. But I've made enough mistakes doing that that I always write to a new file, and verify the contents.

Note, I originally had an if statement in that code. That was most likely wrong. That would have only copied over lines that matched the regular expression "thisgoesout" (replacing it with "thisgoesin" of course) while silently gobbling up the rest.

answered 2008-10-29T23:19:08.313

Is there a simple way to do bulk file text substitution in place?

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