Shell Programming and Scripting

export ORACLE_HOME=/usr/lib/oracle/xe/app/oracle/product/10.2.0/server
export PATH=$PATH:$ORACLE_HOME/bin
export ORACLE_SID=XE

sid_dir=`echo $ORACLE_HOME | sed -n 's@^\(\/[^\/]\+\/\).*$@\1@;p'`

$ cat sql_query.sh
#!/bin/bash
# Validate the value of ORACLE_HOME #
# If ORACLE_HOME is empty #
if [ -z $ORACLE_HOME ]
then
        echo "Set the ORACLE_HOME variable"
        exit 1
fi
# If ORACLE_HOME doesn't exist #
if [ ! -d $ORACLE_HOME ]
then
        echo "The ORACLE_HOME $ORACLE_HOME does not exist"
        exit 1
fi
# Validate the value of ORACLE_SID #
if [ -z $ORACLE_SID ]
then
        echo "Set the ORACLE_SID variable"
        exit 1
fi
sid_dir=`echo $ORACLE_HOME | sed -n 's@^\(\/[^\/]\+\/\).*$@\1@;p'`
# Check the given ORACLE_SID is valid.
if [ ! -d $sid_dir/oradata/$ORACLE_SID ]
then
        echo "The ORACLE_SID is invalid"
        exit 1
fi

/usr/lib/oracle/xe/oradata

if [ ! -d $sid_dir/oradata/$ORACLE_SID ]
then
echo "The ORACLE_SID is invalid"
exit 1
fi

sed -n 's@^\(\/[^\/]\+\/\).*$@\1@;p'

${ORACLE_HOME}/bin/dbhome