bash script to check whether a username exists-CodePudding

I followed the following thread How to create a bash script in Linux that checks if the user is local or not

I want to check number of arguments number received before checking the username

username=$1                                                                     
                                                                                
id -u $username > /dev/null 2>&1                                                
                                                                                
if [ $# -gt 0 ]; then                                                           
 if [ $? -eq 0 ]; then                                                          
  echo "$username exists"                                                       
  else                                                                          
  echo "$username doesn't exist"                                                
  fi                                                                            
else                                                                            
echo "num of arg are less than expected"                                        
fi

the script doesn't work properly, it always writes that the user exists

CodePudding user response：

As explained by Cyrus in comments, you are trying to test $? at the wrong place, because the test or [ command set $? too.

Better use this:

if getent passwd "$username" &>/dev/null; then
    echo 'user exists'
else
    echo 'user NOT exists'
fi

The getent password <username>, if not match a user, exit with a return code >= 1.
It's boolean logic. No need to test $?.

The same logic appears with id:

id nonexistant || echo "not exists"