commit bash-20130301 snapshot

examples/scripts.v2/cdhist.bash

@@ -0,0 +1,176 @@
+#! /bin/bash
+#
+# cdhist - cd replacement with a directory stack like pushd/popd
+#
+# usage: cd [-l] [-n] [-] [dir]
+#
+# options:
+#	-l	print the cd directory stack, one entry per line
+#	-	equivalent to $OLDPWD
+#	-n	cd to nth directory in cd directory stack
+#	-s	cd to first directory in stack matching (substring) `s'
+#
+# arguments:
+#	dir	cd to dir and push dir onto the cd directory stack
+#
+# If the new directory is a directory in the stack and the options selected
+# it (-n, -s), the new working directory is printed
+#
+# If the variable CDHISTFILE is set, the cd directory stack is loaded from
+# and written to $CDHISTFILE every time `cd' is executed.
+#
+# Note: I got this off the net somewhere; I don't know the original author
+#
+# Chet Ramey
+# chet@po.cwru.edu	
+
+_cd_print()
+{
+	echo -e "$@"
+}
+
+cd()
+{
+	typeset -i cdlen i
+	typeset t
+	
+	if [ $# -eq 0 ]
+	then
+		set -- $HOME
+	fi
+	
+	if [ "$CDHISTFILE" ] && [ -r "$CDHISTFILE" ] # if directory history exists
+	then
+		typeset CDHIST
+		i=-1
+		while read -r t			# read directory history file
+		do
+			CDHIST[i=i+1]=$t
+		done <$CDHISTFILE
+	fi
+	
+	if [ "${CDHIST[0]}" != "$PWD" ] && [ -n "$PWD" ]
+	then
+		_cdins				# insert $PWD into cd history
+	fi
+	
+	cdlen=${#CDHIST[*]}			# number of elements in history
+	
+	case "$@" in
+	-)					# cd to new dir
+		if [ "$OLDPWD" = "" ] && ((cdlen>1))
+		then
+			'_cdprint' ${CDHIST[1]}
+			builtin cd ${CDHIST[1]}
+			pwd
+		else
+			builtin cd "$@"
+			# pwd
+		fi
+		;;
+	-l)					# _cdprint directory list
+		((i=cdlen))
+		while (((i=i-1)>=0))
+		do
+			num=$i
+			'_cdprint' "$num ${CDHIST[i]}"
+		done
+		return
+		;;
+	-[0-9]|-[0-9][0-9])			# cd to dir in list
+		if (((i=${1#-})<cdlen))
+		then
+			'_cdprint' ${CDHIST[i]}
+			builtin cd ${CDHIST[i]}
+			pwd
+		else
+			builtin cd $@
+			# pwd
+		fi
+		;;
+	-*)					# cd to matched dir in list
+		t=${1#-}
+		i=1
+		while ((i<cdlen))
+		do
+			case ${CDHIST[i]} in
+			*$t*)
+				'_cdprint' ${CDHIST[i]}
+				builtin cd ${CDHIST[i]}
+				pwd
+				break
+				;;
+			esac
+			((i=i+1))
+		done
+		if ((i>=cdlen))
+		then
+			builtin cd $@
+			# pwd
+		fi
+		;;
+	*)					# cd to new dir
+		builtin cd $@
+		# pwd
+		;;
+	esac
+
+	_cdins					# insert $PWD into cd history
+	
+	if [ "$CDHISTFILE" ]
+	then
+		cdlen=${#CDHIST[*]}		# number of elements in history
+
+		i=0
+		while ((i<cdlen))
+		do
+			echo ${CDHIST[i]}	# update directory history
+			((i=i+1))
+		done >$CDHISTFILE
+	fi
+}
+	
+_cdins()					# insert $PWD into cd history
+{						# meant to be called only by cd
+	typeset -i i
+
+	i=0
+
+	while (( i < ${#CDHIST[*]} ))		# see if dir is already in list
+	do
+		if [ "${CDHIST[$i]}" = "$PWD" ]
+		then
+			break
+		fi
+		((i=i+1))
+	done
+
+	if (( i>22 ))				# limit max size of list
+	then
+		i=22
+	fi
+
+	while (((i=i-1)>=0))			# bump old dirs in list
+	do
+		CDHIST[i+1]=${CDHIST[i]}
+	done
+
+	CDHIST[0]=$PWD				# insert new directory in list
+}
+	
+# examples
+shopt -s expand_aliases
+
+# go to known place before doing anything
+cd /
+
+echo CDHIST: "${CDHIST[@]}"
+for dir in /tmp /bin - -2 -l
+do
+	cd $dir
+	echo CDHIST: "${CDHIST[@]}"
+	echo PWD: $PWD
+
+done
+
+exit 0