[Pkg-sysvinit-devel] Bug#359717: bash workaround

[Zenaan Harkness]

If using bash, this is what I've come to in my local bashlib,
over the last few years:

isMounted () {
   # make sure a target/ arg is passed in:
   [ -z "$1" ] && return 1
   # turn target into fully qualified filename/ location
   # (not doing so can cause problems with some of the tests I've tried,
   # eg perhaps the one currently used see below):
   DIR=`readlink -f "$1"`

   # Option 1, from: http://arstechnica.com/civis//viewtopic.php?f=16&t=1174539
   #
   #grep -q "$DIR" /proc/mounts
   #[ $? -eq 0 ] && return 0 # Alternatively: "return $?", I guess
   # or alt alternative, make sure no other commands like echo follow :)
   # From url: "For more robust bash scripting, using $? is preferred as it
   # allows you to detect extra error conditions (like the command not
   # existing, or you gave it syntactically invalid arguments, etc.)"

   # Option 2:
   #
   # The following seemed unsophisticated, and clunky, when the /bin/mountpoint
   # command is installed by default, thus option 3 below.  But as can be seen
   # with option 3, the "sophisticated" option is in fact buggy. I emailed
   # this bug to initscripts maintainer, debian and ubuntu, on 20101029.
   # See also: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=359717
   # See also: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=622595
   # See also: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=460898
   #mount | grep "on ${DIR} type" > /dev/null && return 0
   #mount | grep -q "on ${DIR} type" && return 0
   mount | grep -q "on ${DIR} type"

   # Option 3:
   #
   # The following (off the web, and a standard command in debian)
   # fails for a directory mounted on itself,
   # which is needed prior to mount --make-rshared /directory.
   #mountpoint -q ${DIR}
}