Ksh

Korn shell - ksh

if-then

if [[ -e /usr/opt/rpm/bin/rpm ]]
then
    RPM_CMD="/usr/opt/rpm/bin/rpm"
else
    RPM_CMD="/usr/bin/rpm"
fi

# Check if we are running this as the root user.
if [[ "$(/usr/bin/id -u)" != "0" ]]
then
    echo "This script must be run as root."
    exit 1
fi

Check AIX Version

# First check the AIX version.
oslvl=`/usr/bin/oslevel`
aix_ver=$(/usr/bin/lslpp -qLc bos.rte | /usr/bin/awk -F':' '{print $3}')
af1=$(echo $aix_ver | /usr/bin/cut -d"." -f1)
af2=$(echo $aix_ver | /usr/bin/cut -d"." -f2)
af3=$(echo $aix_ver | /usr/bin/cut -d"." -f3)
if [[ "$oslvl" = "7.1.0.0" ]]
then
    if [[ ( ! $af1 -ge 7 ) || ( ! $af2 -ge 1 ) || ( ! $af3 -ge 3 ) ]]
    then
        echo "dnf and dependencies can be installed on AIX 7.1.3 and higher versions."
        exit 1
    fi
else
    if [[ ( ! $af1 -ge 7 ) || ( ! $af2 -ge 1 ) ]]
    then
         echo "dnf and dependencies can be installed on AIX 7.1.3 and higher versions."
         exit 1
     fi
fi