This is a shell question, but you didn't specify which shell you use. I answered for the two most common shells.

If your script takes multiple file names:

# bash
script *

# cmd
perl -e"@ARGV = glob('*'); do 'script' or die $@||$!"
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If you're script takes a single file name:

# bash
for q in * ; do script "$q" ; done

# cmd
for %q in (*) do script "%q"
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Not quite right. Both bash versions will leave out the "hidden" files with names starting with a ., and they will process every other directory entry, not just ordinary files, but also special files like symlinks, directories, device nodes, pipes. The cmd for loop also skips files with the hidden bit set.

Alexander

--
Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)

More like insufficient information in the question, so I answered the typical case. Should the OP answer me the following questions and specify the target shell, I'll provide.

• Should directory "." be included? (I assumed no)
• Should directory ".." be included? (I assumed no)
• Should other directories be included? (I assumed yes)
• Should other non-plain files be included? (I assumed yes)
• Should other hidden files be included? (I assumed no)
• Should subdirectories be visited recursively? (I assumed no)

What is the best way to do this?

• Fastest
• Most platform-independent
• Least memory usage

If all you want to do is print out lines of files which match the string 'foo', Unix grep would be a good choice:

grep foo dir/*
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I'm a fan of File::Find for directory traversing, if you prefer using Perl rather than the shell. Here is some code:

#!perl
use strict;
use warnings;

use File::Find;

my $dir = shift;
die 'No directory' unless $dir;

find(
    sub {
#    $File::Find::dir is the current directory name,
#    $_ is the current filename within that directory
#    $File::Find::name is the complete pathname to the file.

#   Process file here...
    },
    $dir
);

__END__
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You could use file tests, regex matches, etc. to filter out the files that you want.

if you prefer bash way, keep in mind that there is a limit max command line length or max arguments count.

# files only in current directory (also hidden)
find . -type f -maxdepth 2 -print0 | xargs -0 script.pl

# all files in all subdirectories
find . -type f -print0 | xargs -0 script.pl

# or run script for every file
find . -type f -exec script.pl {} \;
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I would like the output files to rewrite the original files. Can you show me how to do that?

For example, look at In place editing of text files.

See also:

• Super Search where title contains all of "edit", "file", "place"
• perlopentut
Hit the books and write some code.