Perl: How to search a file named ".cfg" in a directory and all it's parent directories - perl

Question

How to search a file named ".cfg" in a directory and all it's parent directories
I am fetching the name as below code but i would like to know if there is any better way to do it.
Also i would like to know the recursive way to do the same.
sub get_p4_config_updir($ $)
{
my ($client_root, $cfg_file) = #_;
# Dir from where search starts - it's a client root here
my $cur_dir = $client_root;
printf("**** cur_dir: $cur_dir ****\n");
my $slashes = $cur_dir =~ y/\///;
printf("**** no of back slashes: $slashes ****\n");
while($slashes > 2) {
my ($parent_dir, $b) = $cur_dir =~ /(.*)\/(.*)/;
printf("**** parent_dir: $parent_dir, b: $b ****\n");
$slashes--;
if (-e "$cur_dir/$cfg_file") {
printf("**** File exists in dir: $cur_dir ****\n");
return $cur_dir;
}
$cur_dir = $parent_dir;
}
return "";
}
my $cfg = '.cfg';
my $dir = '/user/home/wkspace/abc/def/MAIN';
my $path = get_p4_config_updir($dir, $cfg);
if ($path ne "") {
printf("**** File exists in dir: $path ****\n");
} else {
printf("**** File not found ****\n");
}

Answer 1

An example using Path::Tiny:
#!/usr/bin/env perl
use warnings;
use strict;
use feature qw/say/;
use Path::Tiny;
# Returns a Path::Tiny object to the directory containing the file
# being looked for, or undef if not found.
sub get_p4_config_updir {
my ($client_root, $cfg_file) = #_;
my $dir = path($client_root)->realpath;
while (1) {
# say "Looking at $dir";
if ($dir->child($cfg_file)->exists) {
return $dir;
} elsif ($dir->is_rootdir) {
return undef;
} else {
$dir = $dir->parent;
}
}
}
my $cfg = '.cfg';
my $dir = '/user/home/wkspace/abc/def/MAIN';
say get_p4_config_updir($dir, $cfg) // "File not found";
Or a version that's similar to #rajashekar's idea of walking the directory tree by using chdir to get each directory's parent. This one uses File::chdir, which lets you localize changes to the current working directory (and restores the original when the function/scope exits), as well as providing a handy array view of the current directory and its parents that can be manipulated:
use File::chdir;
...
sub get_p4_config_updir {
my ($client_root, $cfg_file) = #_;
local $CWD = $client_root; # Magic happens here
while (1) {
# say "Looking at $CWD";
if (-e $cfg_file) {
return $CWD;
} elsif ($CWD eq "/") {
return undef;
} else {
pop #CWD; # CDs to the next parent directory
}
}
}

Answer 2

You can use core libraries to do this in a platform independent, readable way without having to use cwd and possibly causing action at a distance effects in the rest of your code:
#!/usr/bin/env perl
use strict;
use warnings;
use File::Spec::Functions qw(catfile rel2abs updir);
sub get_p4_config_updir
{
my ($dir, $file) = #_;
$dir = rel2abs($dir);
do {
my $path = catfile $dir => $file;
return $dir if -e $path;
return if $dir eq (my $new_dir = rel2abs(catfile $dir, updir));
$dir = $new_dir;
} while ('NOT_DONE');
return;
}
sub main {
my ($cfg, $dir) = #_;
my $path = get_p4_config_updir($dir, $cfg);
if (defined $path) {
printf("Found '%s' in '%s'\n", $cfg, $path);
}
else {
printf(
"Did not find '%s' in '%s' or any of its parent directories\n",
$cfg,
$dir,
);
}
}
main(#ARGV);
Output:
C:\Users\u\AppData\Local\Temp> perl p.pl linux.bin .
Found 'linux.bin' in 'C:\'

Answer 3

Why deal with pathnames, when you can walk the directory structure up with .. ?
if the file exists in the current directory return it.
else go up .. and the repeat the process.
use Cwd qw(cwd);
sub search_up {
my ($dir, $file) = #_;
chdir($dir);
while (1) {
if (-e $file) {
print "$file exists in $dir\n";
return $dir;
} elsif ($dir eq "/") {
return;
} else {
chdir("..");
$dir = cwd;
}
};
}

Answer 4

Please see if following code snippet complies with your requirements.
The script is looking for configuration file toward root of filesystem, found filenames are stored in an array #found.
use strict;
use warnings;
use feature 'say';
my $dir = '/user/home/wkspace/abc/def/MAIN';
my $ext = 'cfg';
my($cwd,#found);
for( split('/',$dir) ) {
$cwd .= "$_/";
push #found, glob( $cwd . "*\.$ext" );
}
if( #found ) {
say for #found;
} else {
say 'No file(s) was found';
}
exit 0;
Following code snippet is looking for configuration files away from root filesystem starting from $dir.
If any files found then they will be stored under array reference $found and then printed out on the terminal.
If no files get found then you will be informed with a message.
use strict;
use warnings;
use feature 'say';
my $dir = '/user/home/wkspace/abc/def/MAIN';
my $ext = 'cfg';
my $found = find($dir,$ext);
if( $found ) {
say for #$found;
} else {
say 'No file(s) was found';
}
exit 0;
sub find {
my $dir = shift;
my $ext = shift;
my $ret;
for( glob("$dir/*") ) {
push #$ret, $_ if /\.$ext\z/;
if( -d ) {
my $found = find($_,$ext);
push #$ret, #$found if $found;
}
}
return $ret;
}