Are you use-ing strict, warnings, and Fcntl ':flock' ? If you call flock while LOCK_EX is seen as undef or zero (in numeric context), you won't get the effect you want, and the semaphore will indeed fail silently.

$ perl -e'print +LOCK_EX, $/'
LOCK_EX
$ perl -e'print 0+LOCK_EX, $/
0
$ perl -Mwarnings -e'print 0+LOCK_EX, $/'
Argument "LOCK_EX" isn't numeric in addition (+) at -e line 1.
0
$ perl -Mstrict -Mwarnings -e'print 0+LOCK_EX, $/'
Bareword "LOCK_EX" not allowed while "strict subs" in use at -e line 1
+.
Execution of -e aborted due to compilation errors.
$ perl -Mstrict -Mwarnings -MFcntl=:flock -e'print 0+LOCK_EX, $/'
2
$

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After Compline,
Zaxo

In reply to Re: Does Semaphore Work? by Zaxo
in thread Safe Counter by Gorby

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