15 May 2007 Shell script for removing duplicate files

The following shell script finds duplicate (2 or more identical) files and outputs a new shell script containing commented-out rm statements for deleting them.
You then have to edit the file to select which files to keep – the script can’t safely do it automatically!

OUTF=rem-duplicates.sh;
echo "#! /bin/sh" > $OUTF;
find "$@" -type f -print0 |
  xargs -0 -n1 md5sum |
    sort --key=1,32 | uniq -w 32 -d --all-repeated=separate |
    sed -r 's/^[0-9a-f]*( )*//;s/([^a-zA-Z0-9./_-])/\\\1/g;s/(.+)/#rm \1/' >> $OUTF;
chmod a+x $OUTF; ls -l $OUTF

Example output (rem-duplicates.sh)

#! /bin/sh
#rm ./gdc2001/113-1303_IMG.JPG
#rm ./reppulilta/gdc2001/113-1303_IMG.JPG

#rm ./lissabon/01-01-2001/108-0883_IMG.JPG
#rm ./kuvat\ reppulilta/lissabon/01-01-2001/108-0883_IMG.JPG

#rm ./gdc2001/113-1328_IMG.JPG
#rm ./kuvat\ reppulilta/gdc2001/113-1328_IMG.JPG

Explanation

1. write output script header
2. list all files recursively under current directory
3. escape all the potentially dangerous characters with xargs
4. calculate MD5 sums
5. find duplicate sums
6. strip off MD5 sums and leave only file names
7. escape strange characters from the filenames
8. write out commented-out delete commands
9. make the output script writable and ls -l it

Tags: bash, find, JPG, md5, md5sum, sed, sort, uniq, xargs

Posted by Hans-Henry Jakobsen

md5sum -b *.JPG > checksum.md5

# Change the separator to allow for filenames containing spaces
# (the default is " \t\n", which confuses the for loop)
IFS=$'\n'
FOLDERS=`find /Volumes/disk\ 1/Pictures/Photos -type d | sed 's/ /\\ /g'`
for FOLDER in $FOLDERS; do
# mind you, this will only work with absolute pathnames
if [ -d $FOLDER ]; then
  echo "$0: INFO: Processing" $FOLDER
  cd $FOLDER
  for FILE in `ls -1|grep -i .jpg`; do
    echo "$0: INFO: Checking $FILE"
    djpeg -outfile /dev/null $FILE
    if [ $? -ne 0 ]; then
      echo "$0: ERROR: $FOLDER/$FILE is unreadable as JPEG"
    fi
  done
  if [ -e MD5SUMS ]; then
    md5sum -b -c MD5SUMS 2>&1 > /dev/null
    if [ $? -eq 1 ]; then
      echo "$0: ERROR: in $FOLDER:"
      md5sum -c MD5SUMS | grep FAILED 2>&1
    fi
  else
    echo "$0: WARNING: no MD5SUMS in $FOLDER, creating..."
    md5sum -b *.* > MD5SUMS
    # The obvious bit, in retrospect
    chown username:groupname MD5SUMS
  fi
fi
done