version.sh

#!/bin/bash
# enable debug
#set -x

# variables
VERSIONFILE="$HOME/current-version.sh"

# functions
function saveVersion () {
	echo "#!/bin/bash
	MAJOR=${1}
	MINOR=${2}
	MAINT=${3}
	BUILD=${4}" > $5
}

# load current VERSION
. $VERSIONFILE

# main
# check paramater to see which number to increment
case $1 in
	release)
		MAJOR=$[$MAJOR + 1]
		MINOR=0
		MAINT=0
		BUILD=0
		;;
	feature)
		MINOR=$[$MINOR + 1]
		;;
	maint)
		MAINT=$[$MAINT + 1]
		;;
	bug)
		BUILD=$[$BUILD + 1]
		;;
	current)
		echo "Current version: ${MAJOR}.${MINOR}.${MAINT}.${BUILD}"
		exit 0
		;;
	*)
		echo "Current version: ${MAJOR}.${MINOR}.${MAINT}.${BUILD}"
		echo " "
		echo "Usage: $(basename $0) (current || release || feature || maint || bug)"
  		exit 1
esac

# echo the new VERSION number
echo "NEW VERSION: ${MAJOR}.${MINOR}.${MAINT}.${BUILD}"
saveVersion "${MAJOR}" "${MINOR}" "${MAINT}" "${BUILD}" "$VERSIONFILE"

exit 0

Here's a suggested revision of that shell script:

#!/bin/bash
# enable debug
#set -x

# variables
VERSIONFILE="$HOME/current-version.sh"

# functions
function saveVersion () {
	echo "#!/bin/bash
	MAJOR=${1}
	MINOR=${2}
	MAINT=${3}
	BUILD=${4}" > $5
}

# load current VERSION
. $VERSIONFILE

# main
# check paramater to see which number to increment
case $1 in
	release)
		MAJOR=$[$MAJOR + 1]
		MINOR=0
		MAINT=0
		BUILD=0
		;;
	feature)
		MINOR=$[$MINOR + 1]
		;;
	maint)
		MAINT=$[$MAINT + 1]
		;;
	bug)
		BUILD=$[$BUILD + 1]
		;;
	current)
		echo "Current version: ${MAJOR}.${MINOR}.${MAINT}.${BUILD}"
		exit 0
		;;
	*)
		echo "Current version: ${MAJOR}.${MINOR}.${MAINT}.${BUILD}"
		echo " "
		echo "Usage: $(basename $0) (current || release || feature || maint || bug)"
  		exit 1
esac

# echo the new VERSION number
echo "NEW VERSION: ${MAJOR}.${MINOR}.${MAINT}.${BUILD}"
saveVersion "${MAJOR}" "${MINOR}" "${MAINT}" "${BUILD}" "$VERSIONFILE"

exit 0