kshenv

linux下bash的源码

#
# .kshenv -- functions and aliases to provide the beginnings of a ksh 
#	     environment for bash.
#
# Chet Ramey
# [e-mail]
#
#
# These are definitions for the ksh compiled-in `exported aliases'.  There
# are others, but we already have substitutes for them: "history", "type",
# and "hash".
#
alias r="fc -e -"
alias functions="typeset -f"
alias integer="typeset -i"
alias nohup="nohup "
alias true=":"
alias false="let 0"
alias hist="fc"

#
# An almost-ksh compatible `whence' command.  This is as hairy as it is 
# because of the desire to exactly mimic ksh (whose behavior was determined
# empirically).
# 
# This depends somewhat on knowing the format of the output of the bash
# `builtin type' command.
#

whence()
{
	local vflag
	local path

	vflag=
	path=
	if [ "$#" = "0" ] ; then
		echo "whence: argument expected"
		return 1
	fi
	case "$1" in
		-v) vflag=1
		    shift 1
		    ;;
		-*) echo "whence: bad option: $1"
		    return 1
		    ;;
		 *) ;;
	esac

	if [ "$#" = "0" ] ; then
		echo "whence: bad argument count"
		return 1
	fi

	for cmd
	do
		if [ "$vflag" ]	 ; then
			echo $(builtin type $cmd | sed 1q)
		else
			path=$(builtin type -path $cmd)
			if [ "$path" ] ; then
				echo $path
			else
				case "$cmd" in
					/*) echo ""
					    ;;
					 *) case "$(builtin type -type $cmd)" in
						"") echo ""
						    ;;
						 *) echo "$cmd"
						    ;;
					    esac
					    ;;
				esac
			fi
		fi
	done
	return 0
}

#
# For real ksh homeboy fanatics, redefine the `type' builtin with a ksh
# version.
#
#type()
#{
#	whence -v "$*"
#}

cd()
{
	case $# in
	0)	builtin cd "$HOME" ;;
	1) 	builtin cd "$@" ;;
	2)	old="$1"
		new="$2"
		dir=$(echo "$PWD" | sed "s:$old:$new:g")
		case "$dir" in
		"$PWD")	echo "bash: cd: bad substitution" >&2 ; return 1 ;;
		*)	echo "$dir"
			builtin cd "$dir"
			;;
		esac
		;;
	*)	echo "cd: wrong arg count" >&2 ; return 1 ;;
	esac
}

#
# ksh print emulation
#
#	print [-Rnprsu[n]] [arg ...]
#
#	-	end of options
#	-R	BSD-style -- only accept -n, no escapes
#	-n	do not add trailing newline
#	-p	no-op (no coprocesses)
#	-r	no escapes
#	-s	no-op (print to the history file)
#	-u n	redirect output to fd n
#

print()
{
	local eflag=-e
	local nflag=
	local fd=1

	OPTIND=1
	while getopts "Rnprsu:" c
	do
		case $c in
		R)	eflag=
			;;
		r)	eflag=
			;;
		n)	nflag=-n
			;;
		u)	fd=$OPTARG
			;;
		p|s)	;;
		esac
	done
	shift $[ $OPTIND - 1 ]

	builtin echo $eflag $nflag "$@" >&$fd
}

# substring function
# this function should be equivalent to the substring built-in which was
# eliminated after the 06/29/84 version
substring ()
{
	local lpat flag str	#local variables
	set -f
	case $1 in
	-l|-L)
		flag=$1
		lpat=$2
		shift 2
		;;
	esac
	# test for too few or too many arguments
	if [ x"$1" = x -o $# -gt 2 ]; then
		print -u2 'substring: bad argument count'
		return 1
	fi
	str=$1
	if [ x"$flag" = x-l ]; then		#substring -l lpat
		str=${str#$lpat}
	elif [ x"$flag" = x-L ]; then
		str=${str##$lpat}		#substring -L lpat
	fi

	if [ x"$2" != x ]; then
		echo ${str%$2}
	else
		echo $str
	fi

	return 0
}