Shell Programming and Scripting

#!/bin/ksh
database=$(echo $@ | sed 's/.*-S \([a-zA-Z0-9]*\).*/\1/')
instance=$(grep "$database" /var/opt/oracle/oratab | awk -F : '{print $1}')
command=$(echo $@ | sed 's/"$database"/"$instance"/')
echo  $command

ksh -x rman_wrap.sh rman_backup.pl -S IRMD51 -io 
+ echo /opt/dba/oraadmin/temp/rman_backup.pl -S IRMD51 -io
+ sed 's/.*-S \([a-zA-Z0-9]*\).*/\1/'
+ database=IRMD51
+ grep IRMD51 /var/opt/oracle/oratab
+ awk -F : '{print $1}'
+ instance=IRMD511
+ echo /opt/dba/oraadmin/temp/rman_backup.pl -S IRMD51 -io
+ sed 's/"$database"/"$instance"/'
+ command='/opt/dba/oraadmin/temp/rman_backup.pl -S IRMD51 -io'
+ echo /opt/dba/oraadmin/temp/rman_backup.pl -S IRMD51 -io
/opt/dba/oraadmin/temp/rman_backup.pl -S IRMD51 -io

sed 's/'"$database"'/'"$instance"'/'

command=$(echo $@ | sed  "s/$database/$instance/")

awk -v s="$database" -v r="$instance" 'i=index($0,s){$0=substr($0,1,i-1) r substr($0,i+length(s))}1'