CODEWITHSUNDEEP
linuxbashshellmount
James
James

Reputation: 25

Shell Mount and check directionairy existence

Just looking for some help with my mounting shell script, wondering if anyone could advice me on how to make it check for the directory at the mount point exists and is empty, or is created by the script if it does not exist

#!/bin/bash

MOUNTPOINT="/myfilesystem"

if grep -qs "$MOUNTPOINT" /proc/mounts; then
    echo "It's mounted."
else
    echo "It's not mounted."

    mount "$MOUNTPOINT"

    if [ $? -eq 0 ]; then
        echo "Mount success!"
    else
        echo "Something went wrong with the mount..."
    fi
fi

Upvotes: 1

Views: 1261

Answers (2)

Attie
Attie

Reputation: 6979

Your use of grep will return any mountpoint that contains the string /myfilesystem in... e.g: both of these:

  • /myfilesystem
  • /home/james/myfilesystem

Prefer to use something more prescriptive like the following:

mountpoint -q "${MOUNTPOINT}"

You can use [ to test if a path is a directory:

if [ ! -d "${MOUNTPOINT}" ]; then
    if [ -e "${MOUNTPOINT}" ]; then
        echo "Mountpoint exists, but isn't a directory..."
    else
        echo "Mountpoint doesn't exist..."
    fi
fi

mkdir -p will create all parent directories, as necessary:

mkdir -p "${MOUNTPOINT}"

Finally, test if a directory is empty by exploiting bash's variable expansion:

[ "$(echo ${MOUNTPOINT}/*)" != "${MOUNTPOINT}/*" ]

It's also a good idea to run scripts with some level of 'safety'. See the set built-in command: https://linux.die.net/man/1/bash

-e      Exit immediately if a pipeline (which may consist of a single simple command), a
        list, or a compound command (see SHELL GRAMMAR above), exits with a non-zero
        status.
-u      Treat unset variables and parameters other than the special parameters "@" and "*"
        as an error when performing parameter expansion.

In full: (note bash -eu)

#!/bin/bash -eu

MOUNTPOINT="/myfilesystem"

if [ ! -d "${MOUNTPOINT}" ]; then
    if [ -e "${MOUNTPOINT}" ]; then
        echo "Mountpoint exists, but isn't a directory..."
        exit 1
    fi
    mkdir -p "${MOUNTPOINT}"
fi

if [ "$(echo ${MOUNTPOINT}/*)" != "${MOUNTPOINT}/*" ]; then
    echo "Mountpoint is not empty!"
    exit 1
fi

if mountpoint -q "${MOUNTPOINT}"; then
    echo "Already mounted..."
    exit 0
fi

mount "${MOUNTPOINT}"
RET=$?
if [ ${RET} -ne 0 ]; then
    echo "Mount failed... ${RET}"
    exit 1
fi

echo "Mounted successfully!"
exit 0

Upvotes: 2

Yuriy Zhigulskiy
Yuriy Zhigulskiy

Reputation: 1492

Here is how can you check directory exist and it is empty:
if [ -d /myfilesystem ] && [ ! "$(ls -A /myfilesystem/)" ]; then echo "Directory exist and it is empty" else echo "Directory doesnt exist or not empty" fi

Upvotes: 1

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