The "stat" function is implemented in Perl as a direct system call OS library call because it is commonly recognized that starting up and shutting down a whole shell process just to stat a file will tend to be a noticeable waste of run time, especially given the very typical usage (like in the code above) that could end up doing this relatively costly business many many times. (update: likewise for unlink, rename, and similar built-ins)

Plus, /usr/bin/stat tends to be one of those "core utilities" that don't actually have equivalent command-line syntax from one unix/linux OS to the next. (update: it might be /usr/local/bin/stat, or as pointed out above, it might not be found at all on some systems)

To clarify the run-time issue... Just for grins I found a directory on my mac laptop (2.2GHz intel core i7, osx 10.8.5, perl 5.12) that happens to contain 12.6K files, and I tried two different scripts: 

$ cat /tmp/j1.pl
#!/usr/bin/perl
use strict;
use warnings;
while (<>) {
    chomp;
    my $stat = `stat $_`;
}

$ cat /tmp/j2.pl
#!/usr/bin/perl
use strict;
use warnings;
while (<>) {
    chomp;
    my $stat = stat $_;
}

$ cd path/with/12.6K_files/

$ ls | time /tmp/j1.pl
       60.05 real        12.76 user        31.45 sys

$ ls | time /tmp/j2.pl
        0.07 real         0.01 user         0.02 sys

[download]
I did it a few times, in both orders (j1 right after j2 and vice-versa), and the results were consistent. Imagine what the difference would be over a whole disk with, say, a million files.

As for the cross-platform portability issue… I have to ask: which OS / version of stat are you using? The version of /usr/bin/stat I have on my mac doesn't support the particular command-line syntax you used, so even if I wanted to run your script, I couldn't.

UPDATE: Oh, I forgot to mention… Have you tried running your script in a directory where file names contain spaces, and/or parens, and/or apostrophes, and/or ampersands, and/or … (I hope you get the idea).

In reply to Re^4: removing files with perl based on age and name by graff
in thread removing files with perl based on age and name by Jocqui

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