Script to ensure a folder used for caching always has x% free space. Generated with new_script http://linuxcommand.org/script_library.php

purgePath

#!/bin/bash
################################################################################
#
# Delete least used files
#
################################################################################

PROGNAME=${0##*/}
PROGDIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
VERSION="0.1"
DRYRUN=0

error_exit() {
  echo -e "${PROGNAME}: ${1:-"Unknown Error"}" >&2
  exit 1
}

graceful_exit() {
    exit
}

usage() {
    echo -e "Usage: $PROGNAME [-h|--help|-n|--dryrun] directory"
}

help_message() {
  cat <<- _EOF_
  $PROGNAME ver. $VERSION
  Find least-accessed files, and delete them

  Will ensure that the relevant disk is less than 70%
  full

  $(usage)

  Example:
    $PROGNAME /some/path/
    Drive /dev/sdb1 has xxx free bytes
     need yyy bytes available
    Finding files to delete ...
    Deleting the following files:

    /some/path/foo.zip
    /some/path/bar.zip

  Options:
  -h, --help   Display this help message and exit.
  -n, --dryrun Simulate only

_EOF_
  return
}

function driveSize {
    stats=`df -P $DIR | awk 'NR>1{print}'`

    DRIVE=`echo $stats | awk '{print $1}'`
    DRIVESIZE=`echo $stats | awk '{print $2}'`

    DRIVEUSED=`echo $stats | awk '{print $3}'`
    TARGETUSED=`expr $DRIVESIZE \* 7 / 10`

    DRIVEFREE=`expr $DRIVESIZE - $DRIVEUSED`
    TARGETFREE=`expr $DRIVESIZE \* 3 / 10`

    BYTESTODELETE=`expr $DRIVEUSED - $TARGETUSED`
}

function findToDelete {
    FILEPATH=`tempfile`

    # find
    #     %A+ - Last access time YYYY-MM-DD:HH:MM:SS.X
    #     %p  - filename
    #     %s  - Size in bytes
    find "$DIR" -printf "%A+::%p::%s\n" \
    | sort > "$FILEPATH.raw"

    cat "$FILEPATH.raw" | awk -v todelete="$BYTESTODELETE" -F "::" '
      BEGIN { deleted=0; }
      {
      deleted += $3;
      if (deleted < todelete) { print $2; }
      }
      ' > "$FILEPATH.processed"
}

function main {
    driveSize;
    echo "Drive $DRIVE has $DRIVEFREE free bytes"
    echo " need $TARGETFREE bytes available"

    if [ $DRIVEFREE -lt $TARGETFREE ];
        then
        echo "Finding files to delete ..."
        findToDelete
        if [ $DRYRUN == 1 ];
        then
            echo "The following files would be deleted:"
            echo ""
            cat "$FILEPATH.processed"
        else
            echo "Deleting the following files:"
            echo ""

            cat "$FILEPATH.processed" | tee | rm
        fi
    else
        echo "No action required at this time"
    fi
}

# Parse command-line
while [[ -n $1 ]]; do
  case $1 in
    -n | --dryrun)
      DRYRUN=1;;
    -h | --help)
      help_message; graceful_exit ;;
    -* | --*)
      usage
      error_exit "Unknown option $1" ;;
    *)
      DIR=$1;;
  esac
  shift
done

if [ "$DIR" == "" ];
then
      usage;
      graceful_exit;
fi

main $DIR