mountesp

#!/bin/bash
#
# Mac OS X script to locate and mount an EFI System Partition (ESP)
#
# Usage:
#
# ./mountesp
#
# This program is copyright (c) 2015 by Roderick W. Smith
#
# This program is licensed under the terms of the GNU GPL, version 3,
# or (at your option) any later version.
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
#
# Revision history:
#
# 0.13.2  -- Fixed bug that caused failure with macOS 11.0 ("Big Sur")
# 0.9.3   -- Initial release (with rEFInd 0.9.3)

# Mount the ESP at /Volumes/ESP or determine its current mount
# point.
MountOSXESP() {
    # Identify the ESP. Note: This returns the FIRST ESP found;
    # if the system has multiple disks, this could be wrong!
    Temp=$(mount | sed -n -E "/^(\/dev\/disk.*) on \/ \(.*$/s//\1/p")
    if [ "$Temp" ]; then
        Temp=$(diskutil list | grep " EFI " | grep -o 'disk.*' | head -n 1)
        if [ -z "$Temp" ]; then
            echo "Warning: root device doesn't have an EFI partition"
        fi
    else
        echo "Warning: root device could not be found"
    fi
    if [ -z "$Temp" ]; then
        Temp=$(diskutil list | sed -n -E '/^ *[0-9]+:[ ]+EFI EFI[ ]+[0-9.]+ [A-Z]+[ ]+(disk[0-9]+s[0-9]+)$/ { s//\1/p
                q
            }' )

        if [ -z "$Temp" ]; then
            echo "Could not find an EFI partition. Aborting!"
            exit 1
        fi
    fi
    Esp=/dev/$Temp
    echo "The ESP has been identified as $Esp; attempting to mount it...."
    # If the ESP is mounted, use its current mount point....
    Temp=$(df -P | grep "$Esp ")
    MountPoint=$(echo "$Temp" | cut -f 6- -d ' ')
    if [[ "$MountPoint" == '' ]] ; then
        if [[ $UID != 0 ]] ; then
            echo "You must run this program as root or using sudo! Exiting!"
            exit 1
        fi
        MountPoint="/Volumes/ESP"
        # echo "MountPoint is $MountPoint"
        mkdir /Volumes/ESP &> /dev/null
        # Some systems have HFS+ "ESPs." They shouldn't, but they do. If this is
        # detected, mount it as such and set appropriate options.
        if  ! mount -t msdos "$Esp" $MountPoint ; then
            if ! mount -t hfs "$Esp" $MountPoint ; then
                printf "Unable to mount ESP!\n\n"
                exit 1
            fi
        fi
    fi
    echo "The ESP is mounted at $MountPoint"
} # MountOSXESP()

#
# Main part of script....
#

case "$OSTYPE" in
    darwin*)
            MountOSXESP
            ;;
    *)
            echo "This script is meant to be run under OS X *ONLY*! Exiting!"
            exit
            ;;
esac