diff any file using opendiff (svn, git, mercurial, fossil)

od.sh

# function for .bash-profile or .bashrc


# od <file> [<file2>]
# diff's the given file using opendiff based on the file's vcs
# supports svn, git, mercurial, fossil, & CVS
# can specify any path, checks are done where the file is
# when file2 is specified, fall back to default opendiff behavior
od()
{
  # check params
  [ $# -eq 0 ] && echo "No files to compare!" >&2 && return 1
  [ $# -ge 1 ] && [ ! -e "$1" ] && echo "File does not exist: $1" >&2 && return 1
  [ $# -ge 2 ] && [ ! -e "$2" ] && echo "File does not exist: $2" >&2 && return 1
  
  if [ $# -ne 1 ]; then
    `exec opendiff "$@"`
    return 0
  fi
  
  dir="$(dirname "$1")"
  file="$(basename "$1")"
  
  # svn check
  if [ -d "$dir/.svn" ] || [ 0 -eq `svn info "$dir" >/dev/null 2>&1; echo $?` ]; then
    # svn 1.6 & before
    if [ -d "$dir/.svn/text-base" ]; then
      # src: http://tlzprgmr.wordpress.com/2009/09/19/opendiffsvn-command-line-shortcut/
      opendiff "$dir/.svn/text-base/$file.svn-base" "$1"
      return 0
    # svn 1.7 & after
    else
      `
      cd "$dir"
      # src: http://stackoverflow.com/questions/1242364/how-can-i-find-the-root-folder-of-a-given-subversion-working-copy#comment15044736_1242548
      root_dir="$(svn info|grep "^Working Copy Root Path")"
      root_dir="/${root_dir#*/}"
      
      # should I validate existence of either "$root_dir/.svn/pristine" or "$root_dir/.svn/wc.db" ??
      rel_path="$(pwd)/$file"
      rel_path="${rel_path#$root_dir}"
      rel_path="${rel_path#*/}"
      
      svnbase_file="$(sqlite3 "$root_dir/.svn/wc.db" "select substr(checksum, 7, 2)||'/'||substr(checksum, 7) from nodes where local_relpath = '${rel_path//\'/''}';")"
      
      opendiff "$root_dir/.svn/pristine/${svnbase_file}.svn-base" "$file"
      `
      return 0
    fi
  fi
  
  # git check
  if [ -d "$dir/.git" ] || [ 0 -eq `cd "$dir"; git rev-parse --git-dir >/dev/null 2>&1; echo $?` ]; then
    `
    cd "$dir"
    git difftool -t opendiff --no-prompt "$file"
    `
    return 0
  fi
  
  # mercurial check
  if [ -d "$dir/.hg" ] || [ 0 -eq `cd "$dir"; hg -q stat >/dev/null 2>&1; echo $?` ]; then
    `
    cd "$dir"
    
    # write original file to temp file
    temp="$(mktemp ".$file.XXXXXX")"
    hg cat -o "$temp" "$file"
    
    # diff file
    opendiff "$temp" "$file"
    
    # remove temp file
    rm -f "$temp"
    `
    return 0
  fi
  
  # fossil check
  if [ 0 -eq `cd "$dir"; fossil info >/dev/null 2>/dev/null; echo $?` ]; then
    `
    cd "$dir"
    
    # preserve current settings
    original="$(fossil settings diff-command|grep local|awk '{print $3}')"
    
    # diff file
    fossil settings diff-command opendiff
    fossil diff "$file"
    
    # revert setting
    if [ 0 -eq ${#original} ]; then
      fossil unset diff-command
    else
      fossil settings diff-command "$original"
    fi
    `
    return 0
  fi
  
  # CVS check
  if [ -d "$dir/CVS" ]; then
    `
    cd "$dir"
    
    # write original file to temp file
    temp="$(mktemp ".$file.XXXXXX")"
    # src: http://hints.macworld.com/article.php?story=20040316115029198
    cvs update -p "$file" > "$temp" 2>/dev/null
    
    # diff file
    opendiff "$temp"  "$file"
    
    # remove temp file
    rm -f "$temp"
    `
    return 0
  fi
  
  # otherwise, throw error
  echo "Unknown vcs" >&2
  return 1
}