a test about cleaning oldest files matching pattern in a directory

testRollFile.sh

#Exemple of configurable cleaner for oldest file in a directory
# Use case of this exemple : 
#   * a script that uses a temp file (writing timestamp in its name for exemple)
#   * by default it removes its temp file at the end (and only this one)
#   * for debug purpose we would like to keep the file, or several historic files
#   * with "KEEP_FILE" we can set : 0 (clean all) 1 (only latest) X (youngest files) "ALL" (keep all files)

#configuration
TARGET_DIR=~/tmp/test
KEEP_FILE=3
FILE_PREFIX=file_
FILE_SUFFIX=.ext

#simulate state for testing
i=0
while [ $i -ne 5 ] ; do
  touch $TARGET_DIR/$FILE_PREFIX$i$FILE_SUFFIX
  i=$(($i + 1))
done
CURRENT_FILE="$FILE_PREFIX$(date +%Y%m%d_%H%M%S)$FILE_SUFFIX"
touch $TARGET_DIR/$CURRENT_FILE

# And now the code

#clean oldest files matching prefix and suffix, keeping $KEEP_FILE files
# - by default ('undefined' or unsupported value) : just removes CURRENT_FILE
# - Number = 0 : removes all dumps
# - Number > 0 : keep this number of files (so if 1 then keep only CURRENT_FILE)
# - "ALL" : keep all files
if [ "x$KEEP_FILE" == "xALL" ]
then
  echo "keep all files"
elif [ $KEEP_FILE -ge 0 ] 2>/dev/null
then
  if [ $KEEP_FILE -ne 0 ] ; then
    echo "current file : $TARGET_DIR/$CURRENT_FILE"
  else
    echo "removing all files"
  fi
  NUMBER=$((KEEP_FILE+1))
  echo "cleaning oldest files (keeping $KEEP_FILE files)"
  cd $TARGET_DIR/
  for each in $( ls -t1 $FILE_PREFIX*$FILE_SUFFIX | tail -n+$NUMBER) ; do echo "remove $each"; rm $each; done
  #Note : I prefer 'foreach' beacause it enables several complex actions in 'do' block,
  #whereas 'xargs' would need a sub-script, and also prints an error when there is nothing to do :
  #ls -t1 $FILE_PREFIX*$FILE_SUFFIX | tail -n+$NUMBER | xargs rm -v
  cd - >/dev/null
else
  echo "remove current file"
  rm $TARGET_DIR/$CURRENT_FILE
fi