Shell Programming and Scripting

Hi,

A newbie question.


Following script gives no output.
===============================

root@srv [~]# cat /etc/redhat-release | awk {'print $1}'
Red

root@srv [~]# cat 123.sh
if (( `cat /etc/redhat-release | awk {'print $1}'` != CentOS )); then { echo "System runs on Redhat Linux. Exiting..."; exit; } fi


root@srv [~]# sh 123.sh
root@srv [~]#

root@srv [~]# if (( `cat /etc/redhat-release | awk {'print $1}'` != CentOS )); then { echo "System runs on Redhat Linux. Exiting..."; exit; } fi
root@srv [~]#



root@srv [~]# sh -x 123.sh
++ cat /etc/redhat-release
++ awk '{print $1}'
+ (( Red != CentOS ))


root@srv [~]#


Please advise or provide a alternative so that I can include it in a shell script that will use up2date, in case it is RHEL ( i am aware RHEL 5 use yum ) and will use yum incase it is CentOS


Thanks

OS=`cat /etc/redhat-release | awk {'print $1}'`
if [ "$OS" != "CentOS" ]
then
echo "System runs on Redhat Linux. Exiting...";
exit;
fi

Does CentOS have the /etc/redhat-release file?

Just test for the existence of the file

Code:

if [[ -f /etc/redhat-release ]] ; then
  OS=redhat
else
  OS=CentOS
fi

Hi,

CentOS does have /etc/redhat-release file

Thanks palsevlohit_123 , it works. Lets extend script abit.

Updating in a moment

If /etc/redhat-release doesnot exit , echo system not running redhat or CentOS or redhat-release file is missing, then do nothing below, if /etc/redhat-release exists , then find the OS flavour and,

## if system is Redhat
OS=`cat /etc/redhat-release | awk {'print $1}'`
if [ "$OS" != "CentOS" ]
then
echo "System runs on Redhat Linux.";

do
up2date -i ncurses dialog nmap
done
exit;
fi

## if system is Centos
echo "System runs on CentOS.";
do
yum -y install ncurses dialog nmap
done



I can run the above script two times and one of them will do the install, yum or up2date. I will look better , if we use the value ( Red or CentOS ) and then build a script like ( nested or whatever you call )


If /etc/redhat-release doesnot exit , echo system not running redhat or CentOS or redhat-release file is missing, then do nothing below

else

OS=`cat /etc/redhat-release | awk {'print $1}'`
if [ "$OS" != "CentOS" ]
then
echo "System runs on Redhat Linux.";
then use the up2date command
else if system runs Centos
then use the yum comand
done

Please try

cat /proc/version

and Grep for words "Red" and "CentOS" you can event get the version from the same.