94

What's the best way to check if a volume is mounted in a Bash script?

What I'd really like is a method that I can use like this:

if <something is mounted at /mnt/foo> 
then
   <Do some stuff>
else
   <Do some different stuff>
fi
  • I was just about to write a script to do this myself. My first thought is to get info out of /etc/mtab But I haven't thumbed through my bash books yet to see if there's a more direct way. – 3dinfluence Aug 5 '09 at 20:23
  • @3dinfluence - yes I know this from a long time ago, but /etc/mtab, /proc/mounts are linked to /proc/self/mounts. (atleast on Fedora 20 it is) – Wilf Jan 16 '14 at 20:24

15 Answers 15

107

Avoid using /etc/mtab because it may be inconsistent.

Avoid piping mount because it needn't be that complicated.

Simply:

if grep -qs '/mnt/foo ' /proc/mounts; then
    echo "It's mounted."
else
    echo "It's not mounted."
fi

(The space after the /mnt/foo is to avoid matching e.g. /mnt/foo-bar.)

  • 7
    Not to mention, a call to mount can hang if the mountpoint is wedged. – Chad Huneycutt Aug 5 '09 at 20:32
  • 7
    Good for linux, not for freebsd or solaris. – chris Aug 5 '09 at 20:34
  • 4
    This is true, chris. Although the question was tagged linux. – Dan Carley Aug 5 '09 at 20:38
  • 2
    I guess this is a philosophical question -- should we attempt to make things portable if possible or should we just assume that all the world's running windows/linux and act accordingly? – chris Aug 5 '09 at 20:47
  • 16
    Actually, you should test for '/mnt/foo ', ie. with a space or you might get a false positive if you had mounted a volume named eg. 'fooks'. I just got that issue with two mount points, 'lmde' and 'lmde-home'. – marlar Aug 12 '11 at 20:21
53
if mountpoint -q /mnt/foo 
then
   echo "mounted"
else
   echo "not mounted"
fi

or

mountpoint -q /mnt/foo && echo "mounted" || echo "not mounted"
  • 4
    Just for information: mountpoint originates in the "initscripts" package in Ubuntu/Debian. – blueyed Sep 25 '12 at 8:49
  • Didn't work for me - :-( – Wilf Jan 16 '14 at 20:25
  • This is the call, that my Vagrant hangs upon. – dhill Jul 28 '15 at 13:51
  • The problem with mountpoint is that it checks, in fact, if a mount point is mounted, but not if a device is mounted. If a device is passed with the -x option it tells you the major/minor device number, but not if it's mounted. – vegatripy Aug 14 '17 at 9:46
6

A script like this isn't ever going to be portable. A dirty secret in unix is that only the kernel knows what filesystems are where, and short of things like /proc (not portable) it'll never give you a straight answer.

I typically use df to discover what the mount-point of a subdirectory is, and what filesystem it is in.

For instance (requires posix shell like ash / AT&T ksh / bash / etc)

case $(df  $mount)
in
  $(df  /)) echo $mount is not mounted ;;
  *) echo $mount has a non-root filesystem mounted on it ;;
esac

Kinda tells you useful information.

  • 1
    The question is tagged linux, so maybe it doesn't have to be portable – Rory Aug 10 '09 at 15:59
6

the following is what i use in one of my rsync backup cron-jobs. it checks to see if /backup is mounted, and tries to mount it if it isn't (it may fail because the drive is in a hot-swap bay and may not even be present in the system)

NOTE: the following only works on linux, because it greps /proc/mounts - a more portable version would run 'mount | grep /backup', as in Matthew's answer..

  if ! grep -q /backup /proc/mounts ; then
    if ! mount /backup ; then
      echo "failed"
      exit 1
    fi
  fi
  echo "suceeded."
  # do stuff here
  • 2
    Upvoted as a good sanity checking alternative. – Dan Carley Aug 5 '09 at 21:11
  • Presumably this method runs into the same problems as Matthew Bloch's answer. – mwfearnley Apr 9 '18 at 10:06
  • yeah, except for the space-in-filename issue mentioned by "Eliptical view" (this greps the whole line, not just an extracted field). The sub-string issue isn't a big deal unless you somehow forget that quoting arguments is a thing you can do. e.g. grep -q ' /backup ' /proc/mounts or mount | grep -q ' /backup '. Or redirect to /dev/null if your grep doesn't support -q (which is in the POSIX spec for grep these days). – cas Apr 9 '18 at 10:48
5

findmnt -rno SOURCE,TARGET "$1" avoids all the problems in the other answers. It cleanly does the job with just one command.


Other approaches have these downsides:

  • Parsing mount's white space is problematic. It's man page now says:

.. listing mode is maintained for backward compatibility only.

For more robust and customizable output use findmnt(8), especially in your scripts.


  • grep -q and grep -s are an extra unnecessary step and aren't supported everywhere.
  • /proc/\* isn't supported everywhere.
  • mountinfo is based on /proc/..
  • cut -f3 -d' ' messes up spaces in path names

Functions:

#These functions return exit codes: 0 = found, 1 = not found

isMounted    () { findmnt -rno SOURCE,TARGET "$1" >/dev/null;} #path or device
isDevMounted () { findmnt -rno SOURCE        "$1" >/dev/null;} #device only
isPathMounted() { findmnt -rno        TARGET "$1" >/dev/null;} #path   only

#where: -r = --raw, -n = --noheadings, -o = --output

Usage examples:

if isPathMounted "/mnt/foo bar";      #Spaces in path names are ok.
   then echo "path is mounted"
   else echo "path is not mounted"
fi

if isDevMounted "/dev/sdb4"; 
   then echo "device is mounted"
   else echo "device is not mounted"
fi

#Universal:
if isMounted "/mnt/foo bar"; 
   then echo "device is mounted"
   else echo "device is not mounted"
fi

if isMounted "/dev/sdb4";
   then echo "device is mounted"
   else echo "device is not mounted"
fi
  • For Linux specific anyway this is really the best approach. I have seen the findmnt(8) command but I never really played with it. Frankly if I were to update some of my scripts that do this type of thing (or make new ones) on a Linux box (or where the command is available) this is what I'd do. – Pryftan Apr 14 '18 at 17:49
2

Since in order to mount, you need to have a directory there anyway, that gets mounted over, my strategy was always to create a bogus file with a strange filename that would never be used, and just check for it's existence. If the file was there, then nothing was mounted on that spot...

I don't think this works for mounting network drives or things like that. I used it for flash drives.

2

How about comparing devices numbers? I was just trying to think of the most esoteric way..

#!/bin/bash
if [[ $(stat -c "%d" /mnt) -ne $(stat -c "%d" /mnt/foo) ]]; then
    echo "Somethin mounted there I reckon"
fi

There a flaw in my logic with that ...

As a Function:

#!/usr/bin/bash
function somethingMounted {
        mountpoint="$1"
        if ! device1=$(stat -c "%d" $mountpoint); then
                echo "Error on stat of mount point, maybe file doesn't exist?" 1>&2
                return 1
        fi
        if ! device2=$(stat -c "%d" $mountpoint/..); then
                echo "Error on stat one level up from mount point, maybe file doesn't exist?" 1>&2
                return 1
        fi

        if [[ $device1 -ne $device2 ]]; then
                #echo "Somethin mounted there I reckon"
                return 0
        else
                #echo "Nothin mounted it seems"
                return 1
        fi
}

if somethingMounted /tmp; then
        echo "Yup"
fi

The echo error messages are probably redundant, because stat will display the an error as well.

  • Actually, would probably have to check the exit status of stat first for each call to make sure the file is there ... not as novel as I thought :-( – Kyle Brandt Aug 5 '09 at 21:08
1

None of these satisfy the use case where a given directory is a sub directory within another mount point. For example, you might have /thing which is an NFS mount to host:/real_thing. Using grep for this purpose on /proc/mounts /etc/mtab or 'mount' will not work, because you will be looking for a mount point that doesn't exist. For example, /thing/thingy is not a mount point, but /thing is mounted on host:/real_thing. The best answer voted on here is actually NOT "the best way to determine if a directory/volumne is mounted". I'd vote in favour using 'df -P' (-P POSIX standards mode) as a cleaner strategy:

dev=`df -P /thing/thingy | awk 'BEGIN {e=1} $NF ~ /^\/.+/ { e=0 ; print $1 ; exit } END { exit e }'` && {
    echo "Mounted via: $dev"
} || {
    echo "Not mounted"
}

The output from running this will be:

Mounted via: host:/real_thing

If you want to know what the real mount point is, no problem:

mp=`df -P /thing/thingy | awk 'BEGIN {e=1} $NF ~ /^\/.+/ { e=0 ; print $NF ; exit } END { exit e }'` && {
    echo "Mounted on: $mp"
} || {
    echo "Not mounted"
}

The output from that command will be:

Mounted on: /thing

This is all very useful if you are trying to create some sort of chroot that mirrors mount points outside of the chroot, within the chroot, via some arbitrary directory or file list.

1

Sorry for bringing this up but I think this is pretty usefull:

if awk '{print $2}' /proc/mounts | grep -qs "^/backup$"; then
    echo "It's mounted."
else
    echo "It's not mounted."
fi

This gets the 2nd column of /proc/mounts (2nd column = mount points).

Then it greps the output. Note the ^ and $, this prevents /backup from matching /mnt/backup or /backup-old etc.

0

grep /etc/mtab for your mount point maybe?

  • 1
    mtab can get out of date or simply not be updated by mount, such as when you use mount -n because / is read-only. – chris Aug 5 '09 at 20:33
  • I agree, but that seemed like the first place to start looking. – Ophidian Aug 5 '09 at 21:30
0

This?:

volume="/media/storage"
if mount|grep $volume; then
echo "mounted"
else
echo "not mounted"
if

From: An Ubuntu forum

0

Although this is a Linux question, why not make it portable when it is easily done?

The manual page of grep says:

Portable shell scripts should avoid both -q and -s and should redirect standard and error output to /dev/null instead.

So I propose the following solution:

if grep /mnt/foo /proc/mounts > /dev/null 2>&1; then
        echo "Mounted"
else
        echo "NOT mounted"
fi
  • 3
    Many UNIX systems do not provide the /proc filesystem – Dmitri Chubarov Apr 27 '12 at 19:09
  • @DmitriChubarov Indeed. Which makes the concept of portability ironic doesn't it? And maybe it's a more recent update but -q and -s are specified by POSIX so there shouldn't be any portability issue with it anyway (now if not before - I've not kept track of what changes happen when). – Pryftan Apr 14 '18 at 17:44
0

Does it need to be any more complicated than this?

mount \
    | cut -f 3 -d ' ' \
    | grep -q /mnt/foo \
  && echo "mounted" || echo "not mounted"
  • 1
    grep -q /mnt/foo will also match mount points /mnt/food and /not/mnt/foo... How about grep -qx /mnt/foo? – rakslice Nov 2 '12 at 0:51
  • @rakslice: that wouldn't work. -x makes grep match only if the whole line matches. – mivk Dec 17 '12 at 22:37
  • 1
    cut -f 3 -d ' ' stumbles when mount path has a space in a filename. – Elliptical view Mar 15 '18 at 14:07
0

Depends what you know about the volume you're checking for.

In the particular case I researched recently, where I was concerned to find if a particular flash drive was mounted, what works most easily is checking for the existence of /dev/disks/by-label/. If the device is plugged in, udev scripts make sure the link exists (and that it is removed when the device is unplugged).

(This is NOT a highly portable answer; it works on many modern Linux distributions, though, and the question was tagged for Linux, and it's a completely different approach from anything so far mentioned so it expands the possibilities.)

-1

I had to do this in Chef for idempotence since when chef-client would run, the run would fail due to the volume already being mounted. At the time I write this, the Chef mount resource has some kind of bug which wouldn't work with attributes the way I needed, so I mounted the volume using the execute resource instead. Here's how I did it:

if not node['docker-server']['mountpoint'] == "none"
  execute "set up mount" do
    user "root"
    command "mount -t ext4 #{node['docker-server']['mountpoint']} #{node['docker-server']['data-dir']}"
    not_if "grep -qs #{node['docker-server']['data-dir']} /proc/mounts"
  end
end

In case of any confusion, in my attributes file, I have the following:

default['docker-server']['mountpoint'] = "/dev/vdc"
default['docker-server']['data-dir'] = "/data"

The if not node['docker-server']['mountpoint'] == "none" is a part of a case statement where if the mount point on the server is not specified, the mount point defaults to none.

  • ...and what does this have to do with the original question?!? – Massimo Aug 13 '15 at 21:50
  • The relation of my Chef recipe comment to the original question is that people are increasingly moving toward automation. Therefore, if somebody comes here wondering how to make this work in a Chef recipe, they will have an answer. In life there are two options: 1) Do the bare minimum and make some people happy, and 2) Go the extra mile. Therefore, instead of marking my post down, accept it for what it is: additional information that supports the accepted answer. – KLaw Aug 14 '15 at 22:30
  • The question was about bash scripts, your answer is about Chef scripting. While it could possibly be useful to someone, it still doesn't bear any relevance to the question. – Massimo Aug 15 '15 at 1:08
  • @KLaw 'Therefore, instead of marking my post down, accept it for what it is: additional information that supports the accepted answer.' I agree and I'm not one to usually down vote (and I haven't here either) but if you have an issue with that type of thing you should maybe add it as an addition to your other points? Might save the other comments. But as for automation that's exactly what bash scripts allow so I fail to see your point. Of course the programmer in me thinks that script above is hideous but that's a language issue more than anything else... – Pryftan Apr 14 '18 at 17:46

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