Question

I’m trying to develop a perl script that looks through all of the user’s directories for a particular file name without the user having to specify the entire pathname to the file.

For example, let’s say the file of interest was focus.qseq. It’s located in /home/path/directory/. At the command line, normally the user would have to specify the pathname to the file like in order to access it, like so: /home/path/directory/focus.qseq.

Instead I want the user just to have to enter sample.qseq in the command line, then the perl script will automatically assign the correct file to a variable. If the file is a duplicate but in separate directories, then the terminal will display the full pathname to those files and the user can better specify the file they meant.

I read about the File::Find module but it doesn’t do quite what I want.

Here’s my best attempt at implementing the code as I described above:

#!/usr/bin/perl
use strict; use warnings;
use File::Find;

my $file = shift;

# I want to search from the top down (you know, recursively) so first I look in the home directory
# I believe $ENV{HOME} is the same as $~/home/user
find(\&wanted, @$ENV{HOME}); 
open (FILEIN, $file) or die "couldn't open $file for read: $!\n";

I don’t really understand how the wanted subroutine works in this module. If anyone knows another way to implement the code I describe above, please feel free to make a suggestion. thank you

EDIT:
What if I wanted to utilize the command line option. Like so:

#!/usr/bin/perl
use strict; use warnings;
use File::Find;
use Getopt::Long qw(GetOptions);

my $file = '';
GetOptions('filename|f=s' => \$file);

# I believe $ENV{HOME} is the same as $~/home/user
find(\&wanted, @$ENV{HOME});
open (FILEIN, $file) or die "couldn't open $file for read: $!\n";

how would the implementation be for this one?

Answer 1

One problem is that you try to open the file without specifying the path. You need to create another variable, say $path. Now, you can pass \&wanted as a reference to a subroutine that you write elsewhere, but you might have to resort to global variables. Using a closure would be better.

Your code might look like this then:

#!/usr/bin/perl
use strict; use warnings;
use File::Find;
use Getopt::Long qw(GetOptions);

my ($file, $path);
GetOptions('filename|f=s' => \$file);

# Set $path when file is found.
my $wanted = sub { $path = $File::Find::name if ($_ eq $file); };

find($wanted, $ENV{HOME});
if (!$path) {
    # complain
}
open (FILEIN, $path) or die "couldn't open $file for read: $!\n";