Understanding the find2perl Result

Question

I worked on a script that would recursively search the file system and delete any file (without directories) that is older than 20 days. I used the command find2perl(which is part of File :: Find ), and that was the result. (I noticed that he does not understand the parameter -delete, so I had to use the old -exec...version.)

(parts of the script are truncated)

sub delete_old_files {
    my ($dev,$ino,$mode,$nlink,$uid,$gid);

    (($dev,$ino,$mode,$nlink,$uid,$gid) = lstat($_)) &&
    -f _ &&
    (int(-M _) > 20) &&
    unlink($_);
}

I understand the part lstat, checking the file -fand unlink, but I'm not sure how it works (int(-M _) > 20). Obviously, it checks the modified date for 20 days, but I have never seen this syntax before, and I'm curious to understand where it comes from and how it works. I am also interested in how it can refer to an iterator as a simple underscore without using $_for -fand part of the time check.

Answer 1

The results of calling lstat are cached. By using _, you avoid multiple calls to lstat.

, stat (, _), , ... ( )

stat:

stat , , no stat , stat stat, lstat filetest .

Answer 2

docs -X:

-M Script , .

_ , -X _ .