I’ve fairly frequently ran into the issue while scripting a mount action of
determining if what I want to mount is already mounted. On Linux, you could
parse /proc/mounts, but that’s neither cross-platform, nor is the format of
/proc/mounts guaranteed not to change. The same problem exists with parsing
the output of the mount command, the format of which not only is not
guaranteed to remain the same, it in fact varies greatly between platforms.
To tackle this problem, I looked into how mount gets it’s information. On BSD
and friends, it uses a function called getmntinfo(3). On Linux,
it uses a function called getmntent(3).
Now that I knew how the different UNIXes that I cared to support got their mount information, I wrote up a program to retrieve and format this mount information.
Know that currently, I only support OS X, but I plan on supporting more operating systems in the future.
You can find the sources for my program on my GitHub page.
Usage: getmntinfo [options] [format]
-q, --quiet Produce no output
-h, --help This help message
-B, --bsize=SIZE Fundamental filesystem block size
-I, --iosize=SIZE Optimal transfer block size
-b, --blocks=COUNT Total data blocks in filesystem
-F, --bfree=COUNT Free blocks in filesystem
-a, --bavail=COUNT Free blocks avail to non-superuser
-n, --files=COUNT Total file nodes in filesystem
-e, --ffree=COUNT Free file nodes in filesystem
-U, --fsid=ID Filesystem identifier
-S, --fsid0=ID Top four bytes of filesystem identifier
-T, --fsid1=ID Bottom four bytes of filesystem identifier
-O, --owner=USER User that mounted the filesystem
-g, --flags=FLAGS Copy of mount exported flags
-s, --fssubtype=TYPE Filesystem sub-type (flavor)
-t, --type=TYPE Type of filesystem
-o, --mntonname=DIR Directory on which mounted
-f, --mntfromname=NAME Mounted filesystem
With this program, determining if something is mounted in a script is as simple as
if getmntinfo -t hfs -o / -f /dev/disk0s2 -q; then
echo "Mounted"
else
echo "Not Mounted"
fi