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

Question

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

Answer 1

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

Answer 2

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.

Answer 3

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

Answer 4

if mountpoint -q /mnt/foo 
then
   echo "mounted"
else
   echo "not mounted"
fi

or

mountpoint -q /mnt/foo && echo "mounted" || echo "not mounted"

Answer 5

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.

Answer 6

grep /etc/mtab for your mount point maybe?

Answer 7

This?:

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

From: An Ubuntu forum

Answer 8

Does it need to be any more complicated than:

`mount | cut -f 3 -d ' ' | grep -q /mnt/foo && echo "mounted" || echo "not mounted"`

?

Answer 9

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.

Answer 10

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