Oraenv enhancement script

#!/bin/ksh
#================================================================
# HEADER
#================================================================
#% SYNOPSIS
#+    Usage: . ${SCRIPT_NAME} [-hsv] [SID]
#%
#% DESCRIPTION
#%    This script does little enhancement on top of the oraenv script.
#%    If no SID specified, it will show a list of all available databases
#%        on your machine to choose from.
#%    If dot(.) is specified, it will automaticaly select $ORACLE_SID
#%        if invalid SID, it will select the first SID in /etc/oratab
#%
#% OPTIONS
#%    -h            Print this help
#%    -s            Silent mode
#%    -v            Print script information
#%
#% EXAMPLES
#%    . ${SCRIPT_NAME} oraclesid
#%    source ${SCRIPT_NAME} -s oraclesid
#%
#================================================================
#- IMPLEMENTATION
#-    version         ${SCRIPT_NAME} 0.0.1
#-    author          Michel VONGVILAY (https://www.uxora.com)
#-    license         CC-BY-SA Creative Commons License
#-    script_id       0
#-    based on        http://www.orafaq.com/scripts/unix/oraenv2.txt
#-
#================================================================
# END_OF_HEADER
#================================================================

  #== usage function ==#
scriptinfo() { headFilter="^#+"
[[ "$1" = "ful" ]] && headFilter="^#[%+]"
[[ "$1" = "ver" ]] && headFilter="^#-"
head -${SCRIPT_HEADSIZE:-99} ${SCRIPT_CALL} | grep -e "${headFilter}" | sed -e "s/${headFilter}//g" -e "s/\${SCRIPT_NAME}/${SCRIPT_NAME}/g"; }
fecho() { [[ $flagOptSilent -eq 1 ]] || echo -e ${*};}
error() { echo -e "ERROR: ${SCRIPT_NAME}: ${*}" 1>&2; }
clean() { unset SCRIPT_HEADSIZE SCRIPT_NAME SCRIPT_CALL DEFAULT_SID ORATAB_FILE ORASID_LIST flagOptSilent;
	unset -f scriptinfo error fecho clean; return 0;}

  #== general variables ==#
SCRIPT_CALL="${BASH_SOURCE:-${.sh.file}}" # Get script file when being sourced
SCRIPT_NAME="$(basename ${SCRIPT_CALL})"
SCRIPT_HEADSIZE=$(grep -sn "^# END_OF_HEADER" ${SCRIPT_CALL} | head -1 | cut -f1 -d: 2>/dev/null)

  #== manage options ==#
flagOptSilent=0
case "$1" in
	-h ) scriptinfo ful; clean; return 0;
	;;
	-s ) flagOptSilent=1; shift;
	;;
	-v ) scriptinfo ver; clean; return 0;
	;;
	-* ) error "OPT: $1: unknown option"; scriptinfo; clean; return 1;
	;;
esac

  #== Check/Set arguments ==#
[[ $# -gt 1 ]] && error "Too many arguments" && scriptinfo 1>&2 && clean && return 2

  #== main script ==#
ORATAB_FILE="/etc/oratab"
[[ ! -e $ORATAB_FILE ]] && error "Cannot find $ORATAB_FILE" && clean && return 3

ORAENV_FILE="$(which oraenv 2>/dev/null)"
[[ "x$ORAENV_FILE" == "x" ]] && error "Cannot find oraenv" && clean && return 3

ORASID_LIST=$(cat $ORATAB_FILE | grep -v "^#" | cut -d: -f1 -s | tr -s "[:blank:]" 2>/dev/null)
DEFAULT_SID=$(echo $ORASID_LIST" " | cut -d' ' -f1 -s 2>/dev/null)
if [[ "x$DEFAULT_SID" == "x" ]]; then
	error "No SID found in $ORATAB_FILE"
	clean; return 4
elif [[ "x$ORACLE_SID" != "x" ]]; then
	ORACLE_SID=$(printf "\n$ORASID_LIST" | grep -i "^${ORACLE_SID}$" 2>/dev/null)
	[[ "x$ORACLE_SID" != "x" ]] && DEFAULT_SID=$ORACLE_SID
	ORACLE_SID=
fi

if [[ "x$1" == "x." ]]; then
	ORACLE_SID=$DEFAULT_SID
elif [[ "x$1" != "x" ]]; then
	ORACLE_SID=$(printf "\n$ORASID_LIST" | grep -i "^${1}$" 2>/dev/null)
fi

[ "x${1}" != "x" ] && [ "x${ORACLE_SID}" = "x" ] \
	&& error "ARG: ${1}: Invalid Oracle SID"

if [ -t 0 ]; then	# Command executed from a terminal
	while [ "x${ORACLE_SID}" = "x" ]; do
		echo
		fecho "$(tput rev)Valid Oracle SIDs are :$(tput rmso)"
		for osid in $ORASID_LIST; do
			osidActive="offline"
			[[ "x$( ps -ef | grep "_pmon_$osid" | grep -v "grep" 2>/dev/null)" != "x" ]] && osidActive="online"
			echo -e "$osid\t($osidActive)"
		done | cat -ub -
		#printf "\n$ORASID_LIST" | awk 'NF' | cat -ub -
		echo -e "\nORACLE_SID = [$DEFAULT_SID] ? \c"
		read ANSWER
		echo
		
		ANSWER=$(echo $ANSWER | tr -s "[:blank:]")
		if [ "x${ANSWER}" = "x" ]; then #Empty Answer
			ANSWER=$DEFAULT_SID
		elif [ -z "${ANSWER//[0-9]}" ]; then # Number Answer
			ANSWER_TMP=$(echo $ORASID_LIST" " | cut -d' ' -f${ANSWER} -s 2>/dev/null)
			[ "x${ANSWER_TMP}" != "x" ] && ANSWER=$ANSWER_TMP
			unset ANSWER_TMP
		fi

		ORACLE_SID=$(printf "\n$ORASID_LIST" | grep -i "^${ANSWER}$" 2>/dev/null)
		[ "x${ORACLE_SID}" = "x" ] && error "ANSWER: ${ANSWER}: Invalid Oracle SID"
	done
elif [ "x$ORACLE_SID" = "x" ]; then	# Set to first entry in oratab
	ORACLE_SID=$DEFAULT_SID
fi

ORACLE_HOME=$(grep "^${ORACLE_SID}:" $ORATAB_FILE | cut -d: -f2 -s 2>/dev/null)

[[ "x$(echo ${PATH} | grep "${ORACLE_HOME}/bin")" = "x" ]] \
	&& PATH=${PATH}:${ORACLE_HOME}/bin

export ORACLE_SID
export ORACLE_HOME
export PATH

ORAENV_ASK=NO
[[ $flagOptSilent -eq 1 ]] \
	&& . ${ORAENV_FILE} > /dev/null \
	|| . ${ORAENV_FILE}
ORAENV_ASK=

fecho "\nORACLE_SID is $(tput rev)$ORACLE_SID$(tput rmso)"
fecho "ORACLE_HOME is $(tput rev)$ORACLE_HOME$(tput rmso)\n"

clean; return 0;