bash_jump

# The j function (which stands for 'jump') lets you
# create short-cut references to any directory and 
# then jump to it later without having to type 
# long, arduous directory paths over and over again.
#
# It has 2 primary functions:
# j -m tagname - creates a jumpmark for the current directory
# j tagname - jump to the directory associated with tagname
#
# Install the tool by naming this file something like .bash_jump in your home
# directory, and then adding the following line to your .bashrc:
# 
# . ~/.bash_jump
#
# This simple trick saves me several hundred keystrokes per day. If you
# want to know just how much it's saving you, try: j -s
#
# Jefferson Smith
# http://creativityhacker.ca
#
# Release Notes
# V 0.2 - added stats feature
#       - added version reporting feature
#       - improved internal documentation
#
# V 0.1 - initial release
#

JVERSION='O.2 (Nov 27, 2010)'
JMARKS=~/.jmarks
JLOG=~/.jmarklog
JDATE=`date +%F`

juseage()
{
	echo "Useage: j [tagname | -m tagname | -l]"
	echo "   j tagname    - Jump to the directory associated with 'tagname'"
	echo "   j -m tagname - Associate 'tagname' with the current directory"
	echo "   j -l         - List all known tagnames and their directories"
	echo "   j -s         - Report some jmark usage statistics"
	echo "   j -h         - List general help description for jmark system"
	echo "   j -v         - Report current version number"
}

j()
{
	case "$1" in
	""		) juseage;;
	"-h" | "-H" | "-help" | "-?"	)
			echo "The JMarks utility simplifies the process of leaping around from directory to directory via the command line. For most users, there are only a handful of directories that are commonly used, but they might have very different locations in the file hierarchy. "
			echo ""
			echo "Often, users write alias statements to jump them to their important directories. But as projects come and go, the locations of the key directories often change too. So rather than constantly having to update the shell files to create aliases, we decided to create JMark."
			echo ""
			echo "JMarks is simply a short-hand system for referring to directory locations with short, user-defined tags called 'hypermarks'. By creating a hypermark in a given directory, the user can return to that directory at any time by simply typing 'j markname'. "
			echo ""
			echo "Creating marks is easy as well. Just type 'j -m markname' and the markname will be associated with your current directory."
			echo ""
			echo "And if you forget what hypermark you assigned to a given directory 'j -l' will list all the known hypermarks in the system."
			echo ""
			echo "If you want to build the hypermark database manually, you'll find it in $JMARKS and the file format should be self explanatory."
			;;
	"-m" | "-M"	) if test -z "$2"
			then
				juseage
			else
				exec 6>&1	#link file descriptor 6 with stdout
				exec >>$JMARKS
				echo "$2	$PWD"
				exec 1>&6 6>&-	#restore stdout
				echo "Directory($PWD) marked as $2"
			fi;;

	"-s" | "-S"	) echo "Statistics"
         if test -f $JLOG 
         then
            jcta=`grep $JDATE $JLOG | cut -d\  -f 2 | wc -c`
            jctc=`grep $JDATE $JLOG | cut -d\  -f 2 | wc -l`
            jctb=`cut -d\  -f 2 $JLOG|wc -c`
            jctd=`cut -d\  -f 2 $JLOG|wc -l`
         fi
         echo "Today you've used JMarks $jctc times, saving $jcta keystrokes"
         echo "Overall, you've used JMarks $jctd times, saving $jctb keystrokes"
         ;;

	"-v" | "-V"	) echo "JMarks, vers. $JVERSION"
         echo "by Jefficus <jeff@smithicus.com>"
         ;;

	"-l" | "-L"	) echo "Listing all hypermarks"
				exec 6<&0  #stuff a reference to the stdin into file id 6
				exec < $JMARKS
				read line
				while test "$line" != ""
				do
					echo "  $line"
					read line
				done
				exec 0<&6 6<&-  #now restore the stdin from file id 6
				;;
	*		) if test -z "$1"
			then
				juseage
			else
				exec 6<&0  #stuff a reference to the stdin into file id 6
				exec < $JMARKS
				read line
				found=0
				mark=`echo $line | awk '{print $1}'`
				dir=`echo $line | awk '{print $2}'`
				while test "$line" != ""
				do
					if test $mark = $1
					then
						echo "  Jmarks recognizes hypermark '$mark'."
						echo "  Jumping to dir: $dir"
						cd $dir
                  echo $JDATE $dir >> $JLOG
						found=1
					fi
					read line
					mark=`echo $line | awk '{print $1}'`
					dir=`echo $line | awk '{print $2}'`
				done
				exec 0<&6 6<&-  #now restore the stdin from file id 6
				if test $found = 0
				then
					echo "  Jmarks unable to recognize requested hypermark ($1)."
					echo "  Use 'j -l' to review known marks."
				fi
			fi;;
	esac
}