use Fcntl ':flock'; # Import LOCK_* constants

# We will use this file path in error messages and function calls.
# Don't type it out more than once in your code.  Use a variable.
my $file = '/path/to/some/file';

# Open the file for appending.  Note the file path is quoted
# in the error message.  This helps debug situations where you
# have a stray space at the start or end of the path.
open(my $fh,'>>',$file) or die "Could not open '$file' - $!";

# Get exclusive lock (will block until it does)
flock($fh,LOCK_EX) or die "Could not lock '$file' - $!";

# Do something with the file here...

# Do NOT use flock() to unlock the file if you wrote to the
# file in the "do something" section above.  This could create
# a race condition.  The close() call below will unlock the
# file for you,but only after writing any buffered data.

# In a world of buffered i/o,some or all of your data may not 
# be written until close() completes.  Always,always,ALWAYS 
# check the return value of close() if you wrote to the file!
close($fh) or die "Could not write '$file' - $!";

一些有用的链接：

> PerlMonks file locking tutorial(有点老)
> flock() documentation

为了回应您的补充问题，我会说，将文件锁定在文件上，或者在文件被锁定时创建一个你称之为“锁定”的文件，当它不再被锁定时将其删除(然后确保你的程序服从那些语义)。