Taking Diff bewteen Two Repositories

I wrote a bash script for taking diffs between two repositories.

#!/bin/bash

SVN_USERNAME=dukesoftware
SVN_PASSWORD=some_password
SVN_COMMON_COMMAND="svn --username $SVN_USERNAME --password $SVN_PASSWORD --non-interactive --ignore-externals --quiet"
SVN_COMMON_UPDATE_COMMAND="$SVN_COMMON_COMMAND update --set-depth infinity"
SVN_COMMON_CHECKOUT_COMMAND="$SVN_COMMON_COMMAND co --depth immediates"
SVN_BASE_URL=http://svn.repository.dummy.com/projects/

# comparison svn urls
SVN_URL1=$SVN_BASE_URL/url1
SVN_URL2=$SVN_BASE_URL/url2

DIR1=target1
DIR2=target2

OUTPUT_DIR=diff_out

EXCLUDE_FILES=(".svn" "jquery-*.min.js")

# To minimize number of checkout files, set below constants
CHECKOUT_DIRS=("dir1" "dir2" "lib")
DIFF_TARGETS=("dir1/sub1" "dir1/sub2" "dir2" "lib")

# function definitions
build_base_diff_command(){
 DIFF_BASE_COMMAND="diff -E -B -b -u -r"
 for exclude_file in "${EXCLUDE_FILES[@]}"
 do
  DIFF_BASE_COMMAND+=" -x $exclude_file" 
 done
}

update_subdirs(){
  for dir in "${CHECKOUT_DIRS[@]}"
  do
    echo update "$SVN_URL1/$dir"
    $SVN_COMMON_UPDATE_COMMAND $DIR1/$dir

    echo update "$SVN_URL2/$dir"
    $SVN_COMMON_UPDATE_COMMAND $DIR2/$dir
    echo ""
  done
}

generate_diff(){
  for dir in "${DIFF_TARGETS[@]}"
  do
    echo "generating diff for $dir ...."
    #DIFF_FILE="$OUTPUT_DIR/diff_$SUBDIR.`eval date +%Y%m%d.%H%M%S`.diff"
    DIFF_FILENAME_BASE=${dir////_}
    DIFF_FILE="$OUTPUT_DIR/diff_$DIFF_FILENAME_BASE.diff"
    $DIFF_BASE_COMMAND $DIR1/$dir $DIR2/$dir > $DIFF_FILE
    echo "diff done - $DIFF_FILE"
    echo ""
  done
}

clean_output_dir(){
  rm -r -f $OUTPUT_DIR
}

setup_output_dir(){
  rm -r -f $OUTPUT_DIR
  mkdir -p $OUTPUT_DIR
}

checkout_base(){
  $SVN_COMMON_CHECKOUT_COMMAND $SVN_URL1 $DIR1
  $SVN_COMMON_CHECKOUT_COMMAND $SVN_URL2 $DIR2
}

checkout_base_if_not_preset(){
  if [ ! -d $DIR1 ]
  then
    $SVN_COMMON_CHECKOUT_COMMAND $SVN_URL1 $DIR1
  fi
  if [ ! -d $DIR2 ]
  then
    $SVN_COMMON_CHECKOUT_COMMAND $SVN_URL2 $DIR2
  fi
}

cleanup_checkout_dirs(){
  echo "Cleaning up checkout directories..."
  rm -r -f $DIR1
  rm -r -f $DIR2
}

generate_diff_count(){
  echo "Calculating diff number of lines...."
  echo "YVALUE=`diff -r -U 0 $DIR1 $DIR2 | grep ^@ | wc -l`" > $OUTPUT_DIR/diff_lines.txt
}

# capture for exit status for each command execution
set -e
set -o pipefail

# entry point
build_base_diff_command
case "$1" in
  clean_diff)
    cleanup_checkout_dirs
    checkout_base
    update_subdirs
    setup_output_dir
    generate_diff
    generate_diff_count
    ;;
  clean)
    cleanup_checkout_dirs
    clean_output_dir
    ;;
  diff_count)
    generate_diff_count
    ;;
  *)
    checkout_base_if_not_preset
    update_subdirs
    setup_output_dir
    generate_diff
    generate_diff_count
    ;;
esac
exit $?

If you would like to learn more about Bash script. I recommend read following books.