exim_lock(8) on Linux
The text d2bddd4b6e81, as Debian 10 (Buster), Debian 9 (Stretch), Debian 8 (Jessie), Debian 7 (Wheezy), Debian 6.0 (Squeeze), Debian 5.0 (Lenny), Debian 4.0 (Etch) shipped it.
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Flags it lists
-
-fcntl -
-interval -
-lockfile -
-mbx -
-q -
-retries -
-timeout -
-v