[Wellington-pm] perl -f check failed

[Grant McLean]

On Wed, 2010-07-21 at 15:13 +1200, Jethro Carr wrote:
> Essentially the script creates a number of text files whilst running and
> checks if any exist using -f - if they do, it knows to use a different
> name for the new file.

That sounds like a classic race condition.  If you check whether the
file exists before you create it then it's possible that another process
might create it between the time your check returns false and when you
create the file.

See "perldoc perlopentut" for a description of using O_EXCL to have the
open fail if the file already exists.  Then check for that specific
error in $! if the open fails.

Cheers
Grant