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Linux and Unix userdel command

userdel commandAbout userdel
userdel syntax
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About userdel

The userdel command deletes a user account and all associated files.

Description

userdel is a low-level utility for removing users. (It is not very user-friendly. In most cases, administrators are advised to use the friendlier deluser utility instead.)

The userdel command modifies the system account files, deleting all entries that refer to the user name LOGIN. The named user must exist.

userdel syntax

userdel [options] LOGIN

Options

-f, --force This option forces the removal of the user account, even if the user is still logged in. It also forces userdel to remove the user's home directory and mail spool, even if another user uses the same home directory or if the mail spool is not owned by the specified user. If USERGROUPS_ENAB is defined to yes in /etc/login.defs and if a group exists with the same name as the deleted user, then this group will be removed, even if it is still the primary group of another user.

Note: This option is dangerous and may leave your system in an inconsistent state.
-h, --help Display a help message, and exit.
-r, --remove Files in the user's home directory will be removed along with the home directory itself and the user's mail spool. Files located in other file systems will have to be searched for and deleted manually.

The mail spool is defined by the MAIL_DIR variable in the login.defs file.
-R CHROOT_DIR, --root CHROOT_DIR Apply changes in the chroot directory CHROOT_DIR and use the configuration files from the same directory.
-Z, --selinux-user Remove any SELinux (Security-Enhanced Linux) user mapping for the user's login.

Configuration

The following configuration variables in /etc/login.defs change the behavior of this tool:

Name Type Description
MAIL_DIR string The mail spool directory. This is needed to manipulate the mailbox when its corresponding user account is modified or deleted. If not specified, a compile-time default is used.
MAIL_FILE string Defines the location of the users mail spool files relatively to their home directory.
MAX_MEMBERS_PER_GROUP number Maximum members per group entry. When the maximum is reached, a new group entry (line) is started in /etc/group (with the same name, same password, and same Group ID).

The default value is 0, meaning that there are no limits in the number of members in a group.

This feature (split group) permits to limit the length of lines in the group file. This is useful to make sure that lines for NIS groups are not larger than 1024 characters.

If you need to enforce such limit, you can use 25.

Note: split groups may not be supported by all tools (including the Shadow toolsuite). You should not use this variable unless you really need it.
USERDEL_CMD string If defined, this command is run when removing a user. It should remove any at/cron/print jobs etc. owned by the user to be removed (passed as the first argument).

The return code of the script is not taken into account.

Here is an example script, which removes the user's cron, at and print jobs:

#! /bin/sh

# Check for the required argument.
if [ $# != 1 ]; then
     echo "Usage: $0 username"
     exit 1
fi

# Remove cron jobs.
crontab -r -u $1

# Remove at jobs.
# Note that it will remove any jobs owned by the same UID,
# even if it was shared by a different username.
AT_SPOOL_DIR=/var/spool/cron/atjobs
find $AT_SPOOL_DIR -name "[^.]*" -type f -user $1 -delete \;

# Remove print jobs.
lprm $1

# All done.
exit 0
USERGROUPS_ENAB boolean If set to "yes", userdel will remove the user's group if it contains no more members, and useradd will create by default a group with the name of the user.

Note that the MAIL_DIR and MAIL_FILE variables are used by each of useradd, usermod, and userdel to create, move, or delete the user's mail spool.

Files

/etc/group Group account information.
/etc/login.defs Shadow password suite configuration.
/etc/passwd User account information.
/etc/shadow Secure user account information.

Exit Status

userdel will exit with one of the following exit codes, depending on what occurred:

0 Success.
1 Couldn't update the passwd file.
2 Invalid command syntax.
6 Specified user doesn't exist.
8 Couldn't delete user because the specified user is currently logged in.
10 Couldn't update group file.
12 Couldn't remove home directory.

Notes

userdel will not allow you to remove an account if there are running processes which belong to this account. In that case, you may have to kill those processes or lock the user's password or account and remove the account later. The -f option can force the deletion of this account.

You should manually check all file systems to ensure that no files remain owned by this user.

You may not remove any NIS attributes on a NIS client. This must be performed on the NIS server.

If USERGROUPS_ENAB is defined to "yes" in /etc/login.defs, userdel will delete the group with the same name as the user. To avoid inconsistencies in the passwd and group databases, userdel will check that this group is not used as a primary group for another user, and will just warn without deleting the group otherwise. The -f option can force the deletion of this group.

userdel examples

userdel -r username

Deletes the account of user username, and removes that user's home directory and associated mail files.

useradd — Add a user to the system.
usermod — Modify a user's account.