Simple Shell script to free-up space on disk based on least recently used files.

mylru.sh

#!/bin/bash -u

#Jean Traullé <jean.traulle@etud.u-picardie.fr>
#Under CC0 <http://creativecommons.org/publicdomain/zero/1.0/deed.fr>

#Default size is 20Mo
SIZE=20971520
#Not in dryrun mode by default
DRYRUN=0
#Not recursive by default
RECURSIVE="-maxdepth 1"

#Default void options
RESTRICTTOUSER=
FOLDERS=
USER=
EXTENSION=
CUMULATEDSIZE=0
VERBOSE=0

#Analysing options with getopts and defining variables
while getopts ":s:nRu:e:v" option
do
    case $option in
        s)
            #Option argument need to be a number
            PATTERN='^[0-9]+$'
            if ! [[ $OPTARG =~ $PATTERN ]]
            then
                echo "Usage: -$option argument (size in bytes) must be a number"
                exit 1
            fi

            #Option argument need to be greater that 0
            if [ $OPTARG -eq 0 ]
            then
                echo "Usage: -$option argument (size in bytes) must be greater than 0"
                exit 1
            fi

            SIZE=$OPTARG
            ;;
        u)
            USER="-user ${OPTARG}"
            ;;
        e)
            #Option argument need to be alphanumeric
            PATTERN='^[a-z]+$'
            if ! [[ $OPTARG =~ $PATTERN ]]
            then
                echo "Usage: -$option argument (extension) must be alphanumeric"
                exit 1
            fi

            EXTENSION="-name *.${OPTARG}"
            ;;
        v)
            VERBOSE=1
            ;;
        R)
            RECURSIVE=
            ;;
        n)
            DRYRUN=1
            ;;
        :)
            echo "-$option option require argument"
            exit 1
            ;;
        \?)
            echo "Invalid -$OPTARG option"
            exit 1
            ;;
    esac
done

#Deleting options and options arguments
shift $((OPTIND-1))

#Script need to have at leat 1 arg
if [ $# -lt 1 ]
then
    echo "Usage: pass at least one directory in argument."
    exit 1
fi

#Converting all path provided to absolute path
for dir in "$@"
do
    if [ -d "$dir" ]
    then
        FOLDERS="${FOLDERS}$(readlink -f $dir) "
    else
        echo "mylru: ${dir} is not a directory"
        exit 1
    fi
done

# Find all files 
#   - with write right (needed to delete file)
#   - with size less that specified -s arg
#   - redirect permission and other error messages to blackhole
#   - exec option to get :
#         - date of last access since epoch
#         - size of file in bytes
#         - path of file
#   - we sort by asc last access date since epoch (after removing = outputed by stat command)
FINDRESULTS=$(find $FOLDERS $RECURSIVE $USER $EXTENSION -type f -writable -size -${SIZE}c 2> /dev/null -exec stat -c="%X:%s:%n" {} \; | cut -d= -f2 | sort -t: -k1n,1)

#If no result, print a message and quit
if [ -z "$FINDRESULTS" ]
then
    echo "mylru: No file meet your criteria. Nothing to delete !"
    exit 1
fi

#Replacing Internal Field Separator by newline symbol after saving it
#to permit cycling through files paths (which contains spaces).
SAVEIFS=$IFS
IFS=$'\n'

echo ""

#For each founded file, extract epoch, size and path from line
for file in $FINDRESULTS
do
    EPOCHFILE=$(echo "$file" | cut -d: -f1)
    DATEFILE=$(date -d@"$EPOCHFILE" +%c)
    FILESIZE=$(echo "$file" | cut -d: -f2)
    FILEPATH=$(echo "$file" | cut -d: -f3-)

    #If we do not exeed $SIZE, process for this file
    #otherwise, we check the next file in the list.
    if [ "$(expr ${CUMULATEDSIZE} + ${FILESIZE})" -lt "${SIZE}" ]
    then
        CUMULATEDSIZE=$(expr ${CUMULATEDSIZE} + ${FILESIZE})

        #If in Dryrun mode, do not delete the file
        if [ "${DRYRUN}" -eq 1 ]
        then
            echo "${FILEPATH}"
        else
            rm "${FILEPATH}"
            echo "rm ${FILEPATH}"
        fi

        #If user require verbose, print some useful info about the file
        if [ "${VERBOSE}" -eq 1 ]
        then
            echo "${FILESIZE}B, last accessed on ${DATEFILE}"
            echo ""
        fi
    fi
done

#Restoring IFS anterior value
IFS=$SAVEIFS

#Prints total scape freed and quit
echo -e "Total space freed ${CUMULATEDSIZE}B\n"
exit 0