source: misc/scripts/minify_if_changed.sh @ 753

#!/bin/sh
#
# This script creates a minified version of a javascript or css
# file if the minified version should be updated (or created).
#
# Usage: ./minify_if_changed <input file> [option]
#       - input file    : the non minified js / css file to be
#                         minified
#       - option        : optional argument. If set, the minified
#                         version will only be created if a
#                         minified version already exists
#
# Example:
# ./minify_if_changed /path/to/my.js    A minified version will
#                                       be created if a previous
#                                       minified version differs
#                                       or does not exist.
# ./minify_if_changed /path/to/my.js 1  A minified version will
#                                       only be created if a
#                                       previous version differs.
#                                       If it does not exist a
#                                       minified version will not
#                                       be created
#
# @Author       Jeroen Wesbeek <J****n.W******@gmail.com>
# @Since        20100729
#
# Revision Information:
# $Author: duh $
# $Date: 2010-07-29 09:09:56 +0000 (do, 29 jul 2010) $
# $Rev: 745 $

SOURCE=$1
ONLY_IF_MINIFIED_ALREADY_EXISTS=$2
DESTINATION=`echo $1|sed 's/\.[A-Za-z]*$/.min\0/g'`
MD5SUM=`which md5sum`
MD5_CURRENT=
MD5_NEW=
TMP_FILE=~/tmp/minified

# got a parameter?
if [ ! $1 ]; then
        echo "Usage: "$0" <input file> [only create if a minified already exists]"
        echo "Example: "$0" bla.js 1"
        exit;
fi

# does the input file exist?
if [ ! -f $1 ]; then
        echo "Usage: "$0" <input file> [only create if a minified already exists]"
        echo "Example: "$0" bla.js 1"
        echo "error: could not find "$1
        exit;
fi

# does the destination exist?
if [ -f $DESTINATION ]; then
        # yes, create an MD5 sum
        MD5_CURRENT=`$MD5SUM -t $DESTINATION | sed 's/ .*$//g'`
elif [ $ONLY_IF_MINIFIED_ALREADY_EXISTS ]; then
        # no need to continue
        exit;
fi

# minify sourcefile
java -jar ~/apps/yuicompressor-2.4.2/build/yuicompressor-2.4.2.jar $SOURCE > $TMP_FILE

# determine the MD5 hash of the generated file
MD5_NEW=`$MD5SUM -t $TMP_FILE | sed 's/ .*$//g'`

# do the MD5 hashes differ?
if [ "$MD5_CURRENT" != "$MD5_NEW" ]; then
        cp $TMP_FILE $DESTINATION
        echo ".created minified version of "$SOURCE" ("$MD5_CURRENT" > "$MD5_NEW")"
fi

# remove temp file
if [ -f $TMP_FILE ]; then
        rm $TMP_FILE > /dev/null
fi