1USERMOD(8) System Management Commands USERMOD(8)
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6 usermod - modify a user account
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9 usermod [options] LOGIN
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12 The usermod command modifies the system account files.
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15 The options which apply to the usermod command are:
16 -a, --append
18 Add the user to the supplementary group(s). Use only with the -G
19 option.
20 -b, --badname
22 Allow names that do not conform to standards.
23 -c, --comment COMMENT
25 update the comment field of the user in /etc/passwd, which is
26 normally modified using the chfn(1) utility.
27 -d, --home HOME_DIR
29 The user's new login directory.
30 If the -m option is given, the contents of the current home
32 directory will be moved to the new home directory, which is created
33 if it does not already exist. If the current home directory does
34 not exist the new home directory will not be created.
35 -e, --expiredate EXPIRE_DATE
37 The date on which the user account will be disabled. The date is
38 specified in the format YYYY-MM-DD. Integers as input are
39 interpreted as days after 1970-01-01.
40 An input of -1 or an empty string will blank the account expiration
42 field in the shadow password file. The account will remain
43 available with no date limit.
44 This option requires a /etc/shadow file. A /etc/shadow entry will
46 be created if there were none.
47 -f, --inactive INACTIVE
49 defines the number of days after the password exceeded its maximum
50 age during which the user may still login by immediately replacing
51 the password. This grace period before the account becomes inactive
52 is stored in the shadow password file. An input of 0 will disable
53 an expired password with no delay. An input of -1 will blank the
54 respective field in the shadow password file. See shadow(5) for
55 more information.
56 This option requires a /etc/shadow file. A /etc/shadow entry will
58 be created if there were none.
59 -g, --gid GROUP
61 The name or numerical ID of the user's new primary group. The group
62 must exist.
63 Any file from the user's home directory owned by the previous
65 primary group of the user will be owned by this new group.
66 The group ownership of files outside of the user's home directory
68 must be fixed manually.
69 The change of the group ownership of files inside of the user's
71 home directory is also not done if the home dir owner uid is
72 different from the current or new user id. This is a safety measure
73 for special home directories such as /.
74 -G, --groups GROUP1[,GROUP2,...[,GROUPN]]]
76 A list of supplementary groups which the user is also a member of.
77 Each group is separated from the next by a comma, with no
78 intervening whitespace. The groups must exist.
79 If the user is currently a member of a group which is not listed,
81 the user will be removed from the group. This behaviour can be
82 changed via the -a option, which appends the user to the current
83 supplementary group list.
84 -l, --login NEW_LOGIN
86 The name of the user will be changed from LOGIN to NEW_LOGIN.
87 Nothing else is changed. In particular, the user's home directory
88 or mail spool should probably be renamed manually to reflect the
89 new login name.
90 -L, --lock
92 Lock a user's password. This puts a '!' in front of the encrypted
93 password, effectively disabling the password. You can't use this
94 option with -p or -U.
95 Note: if you wish to lock the account (not only access with a
97 password), you should also set the EXPIRE_DATE to 1.
98 -m, --move-home
100 moves the content of the user's home directory to the new location.
101 If the current home directory does not exist the new home directory
102 will not be created.
103 This option is only valid in combination with the -d (or --home)
105 option.
106 usermod will try to adapt the ownership of the files and to copy
108 the modes, ACL and extended attributes, but manual changes might be
109 needed afterwards.
110 -o, --non-unique
112 allows to change the user ID to a non-unique value.
113 This option is only valid in combination with the -u option. As a
115 user identity serves as key to map between users on one hand and
116 permissions, file ownerships and other aspects that determine the
117 system's behavior on the other hand, more than one login name will
118 access the account of the given UID.
119 -p, --password PASSWORD
121 defines a new password for the user. PASSWORD is expected to be
122 encrypted, as returned by crypt (3).
123 Note: Avoid this option on the command line because the password
125 (or encrypted password) will be visible by users listing the
126 processes.
127 You should make sure the password respects the system's password
129 policy.
130 -r, --remove
132 Remove the user from named supplementary group(s). Use only with
133 the -G option.
134 -R, --root CHROOT_DIR
136 Apply changes in the CHROOT_DIR directory and use the configuration
137 files from the CHROOT_DIR directory. Only absolute paths are
138 supported.
139 -P, --prefix PREFIX_DIR
141 Apply changes within the directory tree starting with PREFIX_DIR
142 and use as well the configuration files located there. This option
143 does not chroot and is intended for preparing a cross-compilation
144 target. Some limitations: NIS and LDAP users/groups are not
145 verified. PAM authentication is using the host files. No SELINUX
146 support.
147 -s, --shell SHELL
149 changes the user's login shell. An empty string for SHELL blanks
150 the field in /etc/passwd and logs the user into the system's
151 default shell.
152 -u, --uid UID
154 The new value of the user's ID.
155 This value must be unique, unless the -o option is used. The value
157 must be non-negative.
158 The user's mailbox, and any files which the user owns and which are
160 located in the user's home directory will have the file user ID
161 changed automatically.
162 The ownership of files outside of the user's home directory must be
164 fixed manually.
165 The change of the user ownership of files inside of the user's home
167 directory is also not done if the home dir owner uid is different
168 from the current or new user id. This is a safety measure for
169 special home directories such as /.
170 No checks will be performed with regard to the UID_MIN, UID_MAX,
172 SYS_UID_MIN, or SYS_UID_MAX from /etc/login.defs.
173 -U, --unlock
175 Unlock a user's password. This removes the '!' in front of the
176 encrypted password. You can't use this option with -p or -L.
177 Note: if you wish to unlock the account (not only access with a
179 password), you should also set the EXPIRE_DATE (for example to
180 99999, or to the EXPIRE value from /etc/default/useradd).
181 -v, --add-subuids FIRST-LAST
183 Add a range of subordinate uids to the user's account.
184 This option may be specified multiple times to add multiple ranges
186 to a user's account.
187 No checks will be performed with regard to SUB_UID_MIN,
189 SUB_UID_MAX, or SUB_UID_COUNT from /etc/login.defs.
190 -V, --del-subuids FIRST-LAST
192 Remove a range of subordinate uids from the user's account.
193 This option may be specified multiple times to remove multiple
195 ranges to a user's account. When both --del-subuids and
196 --add-subuids are specified, the removal of all subordinate uid
197 ranges happens before any subordinate uid range is added.
198 No checks will be performed with regard to SUB_UID_MIN,
200 SUB_UID_MAX, or SUB_UID_COUNT from /etc/login.defs.
201 -w, --add-subgids FIRST-LAST
203 Add a range of subordinate gids to the user's account.
204 This option may be specified multiple times to add multiple ranges
206 to a user's account.
207 No checks will be performed with regard to SUB_GID_MIN,
209 SUB_GID_MAX, or SUB_GID_COUNT from /etc/login.defs.
210 -W, --del-subgids FIRST-LAST
212 Remove a range of subordinate gids from the user's account.
213 This option may be specified multiple times to remove multiple
215 ranges to a user's account. When both --del-subgids and
216 --add-subgids are specified, the removal of all subordinate gid
217 ranges happens before any subordinate gid range is added.
218 No checks will be performed with regard to SUB_GID_MIN,
220 SUB_GID_MAX, or SUB_GID_COUNT from /etc/login.defs.
221 -Z, --selinux-user SEUSER
223 defines the SELinux user to be mapped with LOGIN. An empty string
224 ("") will remove the respective entry (if any). Note that the
225 shadow system doesn't store the selinux-user, it uses semanage(8)
226 for that.
227
229 You must make certain that the named user is not executing any
230 processes when this command is being executed if the user's numerical
231 user ID, the user's name, or the user's home directory is being
232 changed. usermod checks this on Linux. On other operating systems it
233 only uses utmp to check if the user is logged in.
234 You must change the owner of any crontab files or at jobs manually.
236 You must make any changes involving NIS on the NIS server.
238
240 The following configuration variables in /etc/login.defs change the
241 behavior of this tool:
242 LASTLOG_UID_MAX (number)
244 Highest user ID number for which the lastlog entries should be
245 updated. As higher user IDs are usually tracked by remote user
246 identity and authentication services there is no need to create a
247 huge sparse lastlog file for them.
248 No LASTLOG_UID_MAX option present in the configuration means that
250 there is no user ID limit for writing lastlog entries.
251 MAIL_DIR (string)
253 The mail spool directory. This is needed to manipulate the mailbox
254 when its corresponding user account is modified or deleted. If not
255 specified, a compile-time default is used. The parameter
256 CREATE_MAIL_SPOOL in /etc/default/useradd determines whether the
257 mail spool should be created.
258 MAIL_FILE (string)
260 Defines the location of the users mail spool files relatively to
261 their home directory.
262 The MAIL_DIR and MAIL_FILE variables are used by useradd, usermod, and
264 userdel to create, move, or delete the user's mail spool.
265 If MAIL_CHECK_ENAB is set to yes, they are also used to define the MAIL
267 environment variable.
268 MAX_MEMBERS_PER_GROUP (number)
270 Maximum members per group entry. When the maximum is reached, a new
271 group entry (line) is started in /etc/group (with the same name,
272 same password, and same GID).
273 The default value is 0, meaning that there are no limits in the
275 number of members in a group.
276 This feature (split group) permits to limit the length of lines in
278 the group file. This is useful to make sure that lines for NIS
279 groups are not larger than 1024 characters.
280 If you need to enforce such limit, you can use 25.
282 Note: split groups may not be supported by all tools (even in the
284 Shadow toolsuite). You should not use this variable unless you
285 really need it.
286 SUB_GID_MIN (number), SUB_GID_MAX (number), SUB_GID_COUNT (number)
288 If /etc/subuid exists, the commands useradd and newusers (unless
289 the user already have subordinate group IDs) allocate SUB_GID_COUNT
290 unused group IDs from the range SUB_GID_MIN to SUB_GID_MAX for each
291 new user.
292 The default values for SUB_GID_MIN, SUB_GID_MAX, SUB_GID_COUNT are
294 respectively 100000, 600100000 and 65536.
295 SUB_UID_MIN (number), SUB_UID_MAX (number), SUB_UID_COUNT (number)
297 If /etc/subuid exists, the commands useradd and newusers (unless
298 the user already have subordinate user IDs) allocate SUB_UID_COUNT
299 unused user IDs from the range SUB_UID_MIN to SUB_UID_MAX for each
300 new user.
301 The default values for SUB_UID_MIN, SUB_UID_MAX, SUB_UID_COUNT are
303 respectively 100000, 600100000 and 65536.
304
306 /etc/group
307 Group account information
308 /etc/gshadow
310 Secure group account informatio.
311 /etc/login.defs
313 Shadow password suite configuration
314 /etc/passwd
316 User account information
317 /etc/shadow
319 Secure user account information
320 /etc/subgid
322 Per user subordinate group IDs
323 /etc/subuid
325 Per user subordinate user IDs
326
328 chfn(1), chsh(1), passwd(1), crypt(3), gpasswd(8), groupadd(8),
329 groupdel(8), groupmod(8), login.defs(5), subgid(5), subuid(5),
330 useradd(8), userdel(8).
331shadow-utils 4.13 03/06/2023 USERMOD(8)