Comment 76 for bug 1205384

The behavior described in the previous comment is in use in current xflock4 script for Xfce desktop environment. By the way, I proposed a new xflock4 script that adds light-locker (available in Trusty) as an option for locking: http://bug-attachment.xfce.org/attachment.cgi?id=5288
It uses "command -v" instead of "which" althought both likely work as well. It also defines its own supposedly stricter PATH and expects locking commands to be there. (The said bug report is https://bugzilla.xfce.org/show_bug.cgi?id=3770)