OS evaluate in bash script

Question

i was thinking in way that before run my script , evaluate which operating system that user use ubuntu or solaris , am using this because there is some differences
in command option in each OS such as sed .. , i was trying the following :

sysEval=`grep "ubuntu" | uname -a`

if [ sysEval ]; then

.......some command 

else ....... some command
fi

NOTE That my script will run only in ubuntu or solaris
seems not working !

Answer 1

Instead of parsing uname -a a better idea would be parsing output of cat /etc/*release*.

Answer 2

I'd probably do something like this:

os=$(uname -s)
case $os in
  Linux) 
    distro=$(lsb_release -si)
    case $distro in
      Ubuntu) 
        echo "Ubuntu, great!"
        ;;
      *) 
        echo "Sorry, Linux distribution '$distro' is not supported"
        exit 1
        ;;
    esac
    ;;
  SunOS) 
    echo "SunOS, great!"
    ;;
  *) 
    echo "Sorry, OS '$os' is not supported"
    exit 1
    ;;
esac

Answer 3

 sysEval=cat /etc/*release* | awk 'FNR == 1 {print $1 }' | cut -d\= -f2

Answer 4

There is an environment variable:

echo $OSTYPE