#shell `mogrify` and retain original timestamp

mogrify.sh

#!/bin/bash

# Pass a file to mogrify, but retain the timestamp to the nearest second.
#
# Amend the mogrify line below with the correct parameters.
#
# Parameters:
#    The input file and nothing else.
#
# Return codes:
#    101    The file does not exist or is not a regular file
#    102    Did not have permission to read the file
#    103    Did not have permission to modify the file
#    Any other code: As returned by mogrify.
#
# Taken from: https://ubuntuforums.org/showthread.php?t=1505788

# Find the last parameter.
FILENAME="${1}"

# Check that the file exists and is readable and writeable.
if [[ ! -f ${FILENAME} ]]
then
    echo "The file does not exist or it is not a regular file:  ${FILENAME}" >&2
    exit 101
fi
if [[ ! -r ${FILENAME} ]]
then
    echo "I cannot read the file: ${FILENAME}" >&2
    exit 102
fi
if [[ ! -w ${FILENAME} ]]
then
    echo "I cannot modify the file: ${FILENAME}" >&2
    exit 103
fi

# Record the time stamp to the nearest second.
TIMESTAMP="$( ls -l --time-style='+%Y%m%d%H%M.%S' "${FILENAME}" | cut  --delimiter=' ' --fields=6 )"

# Mogrify the file.

#  ==================================================================================================
# Insert the parameters to mogrify on the line below 'mogrify'. Be sure  to end the line with a
# single backslash.
#  ==================================================================================================
mogrify    \
    -normalize -quality 100% \
    "${FILENAME}"    # Change the line above this one.
#  ==================================================================================================

RETURNCODE=${?}

# Reset the timestamp.
touch -t ${TIMESTAMP} -m "${FILENAME}"
echo "-t ${TIMESTAMP} -m '${FILENAME}'"

# Exit with the appropriate code.
exit ${RETURNCODE}