How do I lock a file in Perl?

Question

What is the best way to create a lock on a file in Perl?

Is it best to flock on the file or to create a lock file to place a lock on and check for a lock on the lock

Answer 1

Here's my solution to reading and writing in one lock...

open (TST,"+< readwrite_test.txt") or die "Cannot open file\n$!";
flock(TST, LOCK_EX);
# Read the file:
@LINES=;
# Wipe the file:
seek(TST, 0, 0); truncate(TST, 0);
# Do something with the contents here:
push @LINES,"grappig, he!\n";
$LINES[3]="Gekke henkie!\n";
# Write the file:
foreach $l (@LINES)
{
   print TST $l;
}
close(TST) or die "Cannot close file\n$!";