[vermaden]

I have written this script some time ago to find duplicated files, they may be compared by file name, size or md5 checksum. Feel free to point any issues with it.

It works with FreeBSD and Linux, partially ported to Solaris, but if md5(1) and stat(1) have the same syntax as in FreeBSD (or Linux) it may also be used on other BSDs or any other UNIX system.

Example output/usage:

% duplicated_files.sh
usage: duplicated_files.sh OPTION DIRECTORY
  OPTIONS: -n   check by name (fast)
           -s   check by size (medium)
           -m   check by md5  (slow)
           -N   same as '-n' but with delete instructions printed
           -S   same as '-s' but with delete instructions printed
           -M   same as '-m' but with delete instructions printed
  EXAMPLE: duplicated_files.sh -s /mnt

% duplicated_files.sh -m tmp
count: 2 | md5: eb36b88619424b05288a0a8918b822f0
  tmp/segoeuib.ttf
  tmp/test/segoeuib.ttf

count: 3 | md5: 4e1e3521a4396110e59229bed85b0cf9
  tmp/cam/fdd/file.htm
  tmp/cam/gf/file.htm
  tmp/cam/nf7/file.htm

% duplicated_files.sh -N tmp
count: 2 | file: segoeuil.ttf
  sudo rm -rf "tmp/segoeuil.ttf"
  sudo rm -rf "tmp/test/segoeuil.ttf"

count: 3 | file: file.htm
  sudo rm -rf "tmp/cam/nf7/file.htm"
  sudo rm -rf "tmp/cam/gf/file.htm"
  sudo rm -rf "tmp/cam/fdd/file.htm"

duplicated_files.sh

#! /bin/sh

# find duplicated files in directory tree
# comparing by file NAME, SIZE or MD5 checksum
# --------------------------------------------
# LICENSE(s): BSD / CDDL
# --------------------------------------------
# vermaden [AT] interia [DOT] pl
# http://strony.toya.net.pl/~vermaden/links.htm

__usage() {
  echo "usage: $( basename ${0} ) OPTION DIRECTORY"
  echo "  OPTIONS: -n   check by name (fast)"
  echo "           -s   check by size (medium)"
  echo "           -m   check by md5  (slow)"
  echo "           -N   same as '-n' but with delete instructions printed"
  echo "           -S   same as '-s' but with delete instructions printed"
  echo "           -M   same as '-m' but with delete instructions printed"
  echo "  EXAMPLE: $( basename ${0} ) -s /mnt"
  exit 1
  }

__prefix() {
  case $( id -u ) in
    (0) PREFIX="rm -rf" ;;
    (*) case $( uname ) in
          (SunOS) PREFIX="pfexec rm -rf" ;;
          (*)     PREFIX="sudo rm -rf"   ;;
        esac
        ;;
  esac
  }

__crossplatform() {
  case $( uname ) in
    (FreeBSD)
      MD5="md5 -r"
      STAT="stat -f %z"
      ;;
    (Linux)
      MD5="md5sum"
      STAT="stat -c %s"
      ;;
    (SunOS)
      echo "INFO: supported systems: FreeBSD Linux"
      echo
      echo "Porting to Solaris/OpenSolaris"
      echo "  -- provide values for MD5/STAT in '$( basename ${0} ):__crossplatform()'"
      echo "  -- use digest(1) instead for md5 sum calculation"
      echo "       $ digest -a md5 file"
      echo "  -- pfexec(1) is already used in '$( basename ${0} ):__prefix()'"
      echo
      exit 1
    (*)
      echo "INFO: supported systems: FreeBSD Linux"
      exit 1
      ;;
  esac
  }

__md5() {
  __crossplatform
  :> ${DUPLICATES_FILE}
  DATA=$( find "${1}" -type f -exec ${MD5} {} ';' | sort -n )
  echo "${DATA}" \
    | awk '{print $1}' \
    | uniq -c \
    | while read LINE
      do
        COUNT=$( echo ${LINE} | awk '{print $1}' )
        [ ${COUNT} -eq 1 ] && continue
        SUM=$( echo ${LINE} | awk '{print $2}' )
        echo "${DATA}" | grep ${SUM} >> ${DUPLICATES_FILE}
      done

  echo "${DATA}" \
    | awk '{print $1}' \
    | sort -n \
    | uniq -c \
    | while read LINE
      do
        COUNT=$( echo ${LINE} | awk '{print $1}' )
        [ ${COUNT} -eq 1 ] && continue
        SUM=$( echo ${LINE} | awk '{print $2}' )
        echo "count: ${COUNT} | md5: ${SUM}"
        grep ${SUM} ${DUPLICATES_FILE} \
          | cut -d ' ' -f 2-10000 2> /dev/null \
          | while read LINE
            do
              if [ -n "${PREFIX}" ]
              then
                echo "  ${PREFIX} \"${LINE}\""
              else
                echo "  ${LINE}"
              fi
            done
        echo
      done
  rm -rf ${DUPLICATES_FILE}
  }

__size() {
  __crossplatform
  find "${1}" -type f -exec ${STAT} {} ';' \
    | sort -n \
    | uniq -c \
    | while read LINE
      do
        COUNT=$( echo ${LINE} | awk '{print $1}' )
        [ ${COUNT} -eq 1 ] && continue
        SIZE=$( echo ${LINE} | awk '{print $2}' )
        SIZE_KB=$( echo ${SIZE} / 1024 | bc )
        echo "count: ${COUNT} | size: ${SIZE_KB}KB (${SIZE} bytes)"
        if [ -n "${PREFIX}" ]
        then
          find ${1} -type f -size ${SIZE}c -exec echo "  ${PREFIX} \"{}\"" ';'
        else
          find ${1} -type f -size ${SIZE}c -exec echo "  {}" ';'
        fi
        echo
      done
  }

__file() {
  __crossplatform
  find "${1}" -type f \
    | xargs -n 1 basename 2> /dev/null \
    | tr '[A-Z]' '[a-z]' \
    | sort -n \
    | uniq -c \
    | sort -n -r \
    | while read LINE
      do
        COUNT=$( echo ${LINE} | awk '{print $1}' )
        [ ${COUNT} -eq 1 ] && break
        FILE=$( echo ${LINE} | cut -d ' ' -f 2-10000 2> /dev/null )
        echo "count: ${COUNT} | file: ${FILE}"
        FILE=$( echo ${FILE} | sed -e s/'\['/'\\\['/g -e s/'\]'/'\\\]'/g )
        if [ -n "${PREFIX}" ]
        then
          find ${1} -iname "${FILE}" -exec echo "  ${PREFIX} \"{}\"" ';'
        else
          find ${1} -iname "${FILE}" -exec echo "  {}" ';'
        fi
        echo
      done 
  }

# main()

[ ${#} -ne 2  ] && __usage
[ ! -d "${2}" ] && __usage

DUPLICATES_FILE="/tmp/$( basename ${0} )_DUPLICATES_FILE.tmp"

case ${1} in
  (-n)           __file "${2}" ;;
  (-m)           __md5  "${2}" ;;
  (-s)           __size "${2}" ;;
  (-N) __prefix; __file "${2}" ;;
  (-M) __prefix; __md5  "${2}" ;;
  (-S) __prefix; __size "${2}" ;;
  (*)  __usage ;;
esac