Locking files with PHP

Hello, I am just starting to use PHP.  I have been using PERL for quite some
time.  I was wondering if there is any specific FILE LOCKING I need to
implement to keep more than one person from altering a text file at the same
time.

For instance, in PERL, you use the flock command to set up an advisory file
lock.  Lets say that if I have a web page with a text based database, and
more than one person wants to write to the file at the same time.  In perl,
if you use flock(FILE, 2).  This causes person A to wait while person B
writes to the file.  flock(FILE, 8) unlocks the file.  Then person A is
allowed to write to the file.

Does the perl equivalent of flock happen automatically in PHP?

If not, how do you lock a file?

Is it an advisory lock, or will it cause an error if two people try to
access the same file at the same time for the same purpose (writing).

Thanks,


===========================
Matthew Toledo
FrogNet Design & Domain Management
[email protected]