if (-f $delTemp){
    unlink $delTemp or die "can't delete >$delTemp< file: $!";
}
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This opens a door for a race condition (https://en.wikipedia.org/wiki/Time_of_check_to_time_of_use): Someone can change the file $delTemp between the stat call inside -f and the unlink call.

The clean way to handle this: Just call unlink. Yes, unlink will fail when $delTemp does not exist. Check $! before calling die. POSIX specifies that unlink will return ENOENT if and only if the file was not found.

Something like the following should do the trick, using %! (available since Perl 5.005):

See also Re^2: Subroutine to delete one file and copy one file to another.

Alexander