How to test if a directory exists?

newbie00 has asked for the wisdom of the Perl Monks concerning the following question:

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Re: How to test if a directory exists? by grep (Monsignor) on Dec 25, 2001 at 00:54 UTC
Use -e to check if a file/dir exists. Then -d to check if it is a directory. You do not really need the -e, but it's nice to know. `#!/usr/bin/perl -w use strict; my $dir = '/etc'; if (-e $dir and -d $dir) { print "SPOON :)\n"; } else { print "spork :(\n"; }` [download] You should really pick up "Programming Perl" it is explained in there. It is also under 'perldoc -d' grep grep> cd pub grep> more beer	[reply] [d/l]
Re: How to test if a directory exists? by tachyon (Chancellor) on Dec 25, 2001 at 00:53 UTC
This will work: `$somedir = "c:/windows"; if (-d $somedir) { print "$somedir exists"; } else { print "$somedir does not exist!"; }` [download] If you have a look at perlman:perlfunc and find -X under the Functions for filehandles, files, or directories you will find a range of file tests that can be applied to files and dirs. cheers tachyon s&&rsenoyhcatreve&&&s&n.+t&"$'$`$\"$\&"&ee&&y&srve&&d&&print	[reply] [d/l]
Re: How to test if a directory exists? by ariels (Curate) on Dec 25, 2001 at 17:24 UTC
`-d pathname` will test if pathname exists and is a directory. If you want more resolution, you can say `if (-d $pathname) { # $pathname exists and is a directory # ... } elsif (-e _) { # $pathname exists, but is NOT a directory # ... } else { # $pathname doesn't even exist # ... }` [download] Note the use of the special pseudo-filehandle `_`: it's used to test the last filehandle tested. See perlfunc for more details of this. In any case, testing for existence of a file or a directory is often indicative of a bug. It is almost always better to try to get what you need in a single operation. For instance, instead of saying `if (-d $d) { open FILE, "$d/$f" or die "Open failed"; } else { die "No directory $d"; }` [download] do just the open: `open FILE, "$d/$f" or die "Open failed";` [download] Let the operating system make sure your path is OK. The first way is subject to an insiduous race condition: directory `$d` could be created between the test `-d $d` and the error message, and the error message would be wrong. This is not too bad; but if some more complex error handling were used, it would be likely to break. So try not to test if you can do something with `-X`; just try to do it. If you can't, the OS will let you know.	[reply] [d/l] [select]
Re: How to test if a directory exists? by Alex the Serb (Monk) on Dec 25, 2001 at 12:32 UTC
to make it a whole here comes all of it (I think): -r File or directory is readable -w File or directory is writable -x File or directory is executable -o File or directory is owned by user -R File or directory is readable by real user, not effective user (di +ffers from -r for setuid programs) -W File or directory is writable by real user, not effective user (di +ffers from -w for setuid programs) -X File or directory is executable by real user, not effective user ( +differs from -x for setuid programs) -O File or directory is owned by real user, not effective user (diffe +rs from -o for setuid programs) -e File or directory exists -z File exists and has zero size (directories are never empty) -s File or directory exists and has nonzero size (the value is the si +ze in bytes) -f Entry is a plain file -d Entry is a directory -l Entry is a symlink -S Entry is a socket -p Entry is a named pipe (a "fifo") -b Entry is a block-special file (like a mountable disk) -c Entry is a character-special file (like an I/O device) -u File or directory is setuid -g File or directory is setgid -k File or directory has the sticky bit set -t isatty() on the filehandle is true -T File is "text" -B File is "binary" -M Modification age in days -A Access age in days -C Inode-modification age in days [download]	[reply] [d/l]