find_sleepd_file() in /usr/lib/pm-utils/functions has the following:

find_sleepd_files()
{
        flist="/etc/pm/sleep.d/*[^~] /usr/lib/pm-utils/sleep.d/*[^~]"
        bases=$(for file in $flist ; do echo $(basename $file) ; done | sort -n)
 

If /etc/pm/sleep.d is empty, then $flist is, literally, "/etc/pm/sleep.d/*[^~]".
We go through the 'for file in $flist' loop precisely once, with $file set to
the same. $(basename $file) evaluates to '*[^~]' and the 'echo' command prints
the filename of every file in the current directory.

Let's just hope that the first filename printed by echo isn't the name of a
program which will do nasty things... :)