Shell Programming and Scripting

#!/bin/bash
#
#	Variables
#
	OLD_PATH=$PATH
	case "$(uname)" in
	   *SunOS*) ORATAB=/var/opt/oracle/oratab
		    ;;
	   *)       ORATAB=/etc/oratab
		    ;;
	esac
#
#	Functions
#
	get_ora_file() {
	# Try to locate the file, if locate is installed
	# Otherwise try find
		if which locate 2>/dev/null >&2
		then	list=$(locate oratab)
		else	list=$(for D in etc opt var $HOME/{etc,opt,var} usr/local/{etc,opt,var} ;do find /$D/ -name oratab 2>/dev/null)
		fi
		[ -z $list ] && return 1
		# Make it selectable if multiple found
		count=$(echo $list | wc -w)
		if [ ${count:-0} -gt 1 ]
		then	select output in $list;do echo $output;return 0;done
		elif [ ${count:-0} -eq 1  ]
		then	echo $list
		else	echo "No oratab could be found"
			return 1
		fi
	}
#
#	Preps
#	
	# Check for default file, if missing, call function, but if the function fails, exit the script
	[ ! -f $ORATAB ] && \
		echo "File $ORATAB not at default location!" >&2 && \
		{ ORATAB=$(get_ora_file) || exit 1 ; }
	grep -v "^#" $ORATAB |while IFS=":" read ORACLE_SID ORACLE_HOME AUTOSTART
	do
		if  ps -eaf |grep "pmon[_]$ORACLE_SID" >/dev/null; then
			echo "My db  : $ORACLE_SID"
			echo "My home: $ORACLE_HOME"
			PATH=$ORACLE_HOME/bin:$OLD_PATH
			sqlplus -s / as sysdba <<-EOF
				select instance_name,status,database_status from v\$instance;
				select * from v\$version;
			EOF
		fi
	done

get_oratab() { # SERVER
# Parse $1 
# and return its according value
	# Make string all small chars
	case "${1,,}" in
	*bd1)	str="/etc/oratab"	;;
	*bd2)	str="/path/oratab"	;;
	*bd3)	str="/path/of/oratab"	;;
	*)		echo "Input \"$1\" is invalid!"
			return 1
			;;
	esac
	echo $str
	return 0
}

ps -fea |grep [p]mon | while read _ _ _ _ _ _ _ ORACLE_SID
do
	ORATAB=$(get_oratab $ORACLE_SID)
	echo "myDB: $ORACLE_SID"
	echo "myHome: $ORATAB"
done