I am new to unix but have a basic understanding. I have a script that reads in a username then uses useradd to create a logon, but if you type a user name then delete it the system tries to change the logged on as. How can I set up a script that stops either a null value or the current user from going any further? I currently have the following written in SCO echo Enter user login name read loginID echo " " echo Enter Full user name read username echo " " gid_def=group share_root=/u/shared # Checks to see if the user exists in the passwd file cut -d":" -f1 /etc/passwd | egrep '^'$loginID'$' > /$data/nuidlog # Looks to see if the nuidlog contains data datasize=`ls -l /$data|tail -1|cut -c 40-41` if [ $datasize = 0 ] then #Create user script clear echo "Adding user... $loginID" /etc/useradd -G$gid_def -c"$username" -d /usr/$loginID $loginID echo "Making user directory..." mkdir /usr/$loginID cp $data/.profiletemp /usr/$loginID/.profile echo "Creating user profile..." echo " " passwd $loginID echo $helpdeskuser "created " $loginID " at " $datenow >> $log/log else echo $loginID ' already in system ' sleep 5 fi

#!/bin/sh echo Enter user login name read loginID # if you're using ksh you can # do this #if [[ -z $loginID ]] #then # echo "null login" # exit #fi # if using sh, try this: # X will equal X if null if [ X$loginID = "X" ] then echo "null login" exit fi # Try this for checking if user exists while read line do if [ `echo $line|cut -d ":" -f1 ` = $loginID ] then echo "$loginID already exists" exit fi done < /etc/passwd

Thanks very much nails I was using sh, I never knew you could run the if like that, I am sure I will use that for many more scripts to come. I did have trouble with the checking if the user exist though, it was a bad statment probably me putting it in the wrong place ;) Can you explain how that script works as I have never seen a done with a read in before. Newbie in Trouble.

Hi: Are you asking to explain this: if [ X$loginID = "X" ] then echo "null login" exit fi First, the spaces around the braces is very important to the shell. This will fail: if [X$loginID = "X"] then . . When appending a variable to another string you create a new string. In the case above, it the contents of loginID is empty/null, then appending the variable didn't change "X". You then know loginID is null and can take appropriate action. The more modern shells have null checks like -z. There also -n which returns true if the length of the variable is zero. Regards, Nails