[NTLUG:Discuss] Bash script way to tell if a filesystem is mounted

[Chris Cox]

Patrick R. Michaud wrote:
> On Sat, May 29, 2010 at 11:07:48AM -0500, Hank Ivy wrote:
>> On Saturday 29 May 2010 09:28 am Ralph Green wrote:
>>>  If a directory and its parent  
>>>  have the same filesystem identifier, then that directory
>>>  is not a filesystem mount point.
>> What will happen if you have multiple levels of mount points?
>>
>> For Example (in /etc/fstab):
>> /dev/md17 /home2 ... 3
>> /dev/md18 /home2/userx ... 4
>>
>> The 3 and the 4 control the order of the mounts.
>> If neither file system is mounted, will the return values be the same?
> 
> Presumably if /home2 isn't mounted, then /home2/userx (the mountpoint)
> doesn't exist.  Unless of course someone has also created /home2/userx 
> in /home2 of the root filesystem, which then gets masked when /home2
> is mounted.
> 
> But yes, what I said above still applies -- if a directory (/home2/userx)
> and its parent (/home2) have the same file system identifier, then
> the directory is not a filesystem mount point.  So if neither /home2
> nor /home2/userx are mounted, then /home2 will have the same filesystem
> identifier as /, and /home2/userx will have the same filesystem identifier
> as /home2 .
> 
> Pm

Also, if it helps, you can grep against /etc/mtab or /proc/mounts