Question

How do I rewrite this script in Korn Shell? It’s in Bash right? I’m a little confused to the actual differences between all the shells… Am I on the right track to converting it to Korn Shell?

usage ()
{
     echo      "usage: ./file.sk user"
}
# test if we have two arguments on the command line
if [[ $# != 1 ]]
then
    usage
    exit
fi

# Search for user
fullname=$(cut -f1 -d: /etc/passwd | grep "$1")
if [[ $? -eq 0 ]]; then
                echo "User already found:"
                grep $1 /etc/passwd
        exit
        else
                #get numbers
                cat /etc/passwd | gawk -F: '{print $3}' | sort -n > currentuid4
                #get last number
                last=`tail -1 currentuid4`
                echo last $last
                #add +1
                newuid=`expr $last + 1`
                #print it
                echo "ADDED: $1 with UID: $newuid"
        exit
fi

Answer 1

I suggest replacing [[ … ]] by [ … ] and using -eq/-ne to make the script more portable on different shells.

usage ()
{
     echo      "usage: ./file.sk user"
}
# test if we have two arguments on the command line                                                                                                            
if [ "$#" -ne 1 ]
then
    usage
    exit
fi

# Search for user                                                                                                                                              
fullname=$(cut -f1 -d: /etc/passwd | grep "$1")
if [ "$?" -eq 0 ]; then
                echo "User already found:"
                grep $1 /etc/passwd
        exit
        else
                #get numbers                                                                                                                                   
                cat /etc/passwd | gawk -F: '{print $3}' | sort -n > currentuid4
                #get last number                                                                                                                               
                last=`tail -1 currentuid4`
                echo last $last
                #add +1                                                                                                                                        
                newuid=`expr $last + 1`
                #print it                                                                                                                                      
                echo "ADDED: $1 with UID: $newuid"
        exit
fi