Shell Programming and Scripting

I have a question about the type of this variable
checkU= sudo cat /etc/passwd: grep $uname: wc -l

I write a script to check the existent of username that get from the keyboard. If there is no username,it will create the username else it show the 'Duplicate name" message.

The problem is it always show 'Duplicate name' although there is not that username in the system.
What do I write wrong? I use the wrong operator?

This is the section of script that have a problem:

Code:

checkU=sudo cat /etc/passwd: grep $uname: wc -l
if [ "$checkU" = "0" ] ; then
       useradd -c "$fullname" $uname
       echo OK
else
        echo Duplicate name
fi

Code:

 
"$checkU" = "0"
 
should be 
 
"$checkU" == "0"

what shell you are using ?

bourne shell

Try this..

Code:

checkU=`grep -c $uname /etc/passwd`
[ "$checkU" -gt "0" ] && echo "Duplicate Name" || useradd -c "$fullname" $uname

It's work. thank you!!