I'm trying to create a user with first and last name and home directory in Users/username, with an expiration date, inactive, with a default UID and GID in the DKEL_dir /etc/skel2. This is what I ran on CentOS:
sudo useradd -m -d /Users/username -s /bin/default/useradd -e $(date. -d "2 days ago" "+%Y-%m-%d") -f -k /etc/skel2 Scott walker
The result I got was:
useradd:invalid numeric argument '-k'
I don't really know why you would want to have this in /Users which isn't a standard directory. Are you absolutely sure you want that? On Linux systems, home directories are normally under /home, I have only seen /Users on macOS or sometimes in cases where there is a centralized server handling users.
Anyway, assuming you do want it in /Users, the first problem is that -f requires an argument. From man useradd:
-f, --inactive INACTIVE
defines the number of days after the password exceeded its maximum
age where the user is expected to replace this password. The value
is stored in the shadow password file. An input of 0 will disable
an expired password with no delay. An input of -1 will blank the
respective field in the shadow password file. See shadow(5)for
more information.
If not specified, useradd will use the default inactivity period
specified by the INACTIVE variable in /etc/default/useradd, or -1
by default.
So -f sets the number of days after the end of the password's expiry date that the user will be made inactive. However, the value you are giving it here isn't valid since you have written -f -k, so the -k is read as the value given to -f. To make the user inactive, specify the expiry date in the past, as you have done, and then just use -f 0 to have the password expire with no delay.
The next issue is that login names cannot contain whitespace so you can't use Scott Walker. To set the first and last name using useradd, you need the -c or --comment options. Again, from man useradd:
-c, --comment COMMENT
Any text string. It is generally a short description of the
account, and is currently used as the field for the user's full
name.
Next, the -s is used to define the user's shell, and /bin/default/useradd isn't a shell, it shouldn't even exist as there should be no /bin/default directory (or any subdirectories in /bin). I don't know what you wanted there, but just not including -s will default to the system's default shell. So, putting all this together:
sudo useradd -m -d /Users/scott \
-e $(date -d "2 days ago" "+%Y-%m-%d") \
-f -1 \
-k /etc/skel2 \
-c "Scott Walker" \
scott
That will create a user named scott, with the full name Scott Walker, the home directory /Users/scott, an expiry date of 2 days ago and a inactive date of yesterday.
For more details, please see the official CentOS documentation.
Try specifying a 0 or -1 with the -f flag. Without the -f flag, useradd will use whatever is configured in the "INACTIVE" variable in /etc/default/useradd, or -1 by default. The /etc/default/useradd conf file is definitely recommended to edit to your liking in a production environment so that every new account starts with the same basic "shell".
From the manpage:
> -f, --inactive INACTIVE
> The number of days after a password expires until the account is permanently disabled. A value of 0
> disables the account as soon as the password has expired, and a value of -1 disables the feature.
I typically only use useradd to create the base shell of a user and then modify the groups and all the many .conf files associated with accounts. I'm all for using all the features, though! There are just too many fat finger variables that I don't want to assume the risk for.
