Bash script if else

Question

I am writing my first bash script to loop through a CSV with old username to new usernames. I only read the new username to make the linux account

while read old_name new_name
do
   new_name="$(tr [A-Z] [a-z] <<< $new_name)"
   echo $new_name
   cmd= useradd -g groupid -s /bin/ksh $new_name >> $LOGFILE 2>&1
   echo password | passwd --stdin $new_name

But some users already exist and don't need a new password. Only the new users need the password.

When a user already exists I get useradd: user 'username' already exists

How can I fix this?

unix.stackexchange.com/q/28526/67817

Tom Fenech
– Tom Fenech

2016-03-07 10:47:31 +00:00
Commented Mar 7, 2016 at 10:47 — Tom Fenech
– Tom Fenech, Commented Mar 7, 2016 at 10:47

Tom Fenech · Accepted Answer · 2016-03-07 16:49:53Z

2

The linked question covers how to determine whether a user already exists but I would suggest making a couple of other modifications to your script:

# always use -r (raw) switch unless you have a specific reason not to
while read -r old_name new_name
do
    new_name=${new_name,,} # convert to lowercase using parameter expansion
    if ! id -u "$new_name" &>/dev/null # check user doesn't exist
    then
        useradd -g groupid -s /bin/ksh "$new_name" &>"$LOGFILE"
        passwd --stdin "$new_name" <<<password # avoid useless echo + pipe
    fi
done

As mentioned in the comments, you may have to resort to your original method to convert $new_user to lowercase if you're using an older version of bash (the ${var,,} syntax is a bash 4 feature). If you use [:upper:] and [:lower:] instead of [A-Z] and [a-z] then your script will be less locale-specific, which may be something to be aware of.

edited Mar 7, 2016 at 16:49

answered Mar 7, 2016 at 11:16

Tom Fenech

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2 Comments

mrdennis86 Over a year ago

Thanks Tom. i will test i tomorrow in my test env.

chepner Over a year ago

${new_name,,} requires bash 4, though. Earlier versions will have to use new_name=$(tr [:upper:] [:lower:] <<< "$new_name").

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