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 to reflect the
13 changes that are specified on the command line.
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16 The options which apply to the usermod command are:
17 -a, --append
19 Add the user to the supplementary group(s). Use only with the -G
20 option.
21 -b, --badnames
23 Allow names that do not conform to standards.
24 -c, --comment COMMENT
26 The new value of the user's password file comment field. It is
27 normally modified using the chfn(1) utility.
28 -d, --home HOME_DIR
30 The user's new login directory.
31 If the -m option is given, the contents of the current home
33 directory will be moved to the new home directory, which is created
34 if it does not already exist. If the current home directory does
35 not exist the new home directory will not be created.
36 -e, --expiredate EXPIRE_DATE
38 The date on which the user account will be disabled. The date is
39 specified in the format YYYY-MM-DD.
40 An empty EXPIRE_DATE argument will disable the expiration of the
42 account.
43 This option requires a /etc/shadow file. A /etc/shadow entry will
45 be created if there were none.
46 -f, --inactive INACTIVE
48 The number of days after a password expires until the account is
49 permanently disabled.
50 A value of 0 disables the account as soon as the password has
52 expired, and a value of -1 disables the feature.
53 This option requires a /etc/shadow file. A /etc/shadow entry will
55 be created if there were none.
56 -g, --gid GROUP
58 The group name or number of the user's new initial login group. The
59 group must exist.
60 Any file from the user's home directory owned by the previous
62 primary group of the user will be owned by this new group.
63 The group ownership of files outside of the user's home directory
65 must be fixed manually.
66 The change of the group ownership of files inside of the user's
68 home directory is also not done if the home dir owner uid is
69 different from the current or new user id. This is a safety measure
70 for special home directories such as /.
71 -G, --groups GROUP1[,GROUP2,...[,GROUPN]]]
73 A list of supplementary groups which the user is also a member of.
74 Each group is separated from the next by a comma, with no
75 intervening whitespace. The groups are subject to the same
76 restrictions as the group given with the -g option.
77 If the user is currently a member of a group which is not listed,
79 the user will be removed from the group. This behaviour can be
80 changed via the -a option, which appends the user to the current
81 supplementary group list.
82 -l, --login NEW_LOGIN
84 The name of the user will be changed from LOGIN to NEW_LOGIN.
85 Nothing else is changed. In particular, the user's home directory
86 or mail spool should probably be renamed manually to reflect the
87 new login name.
88 -L, --lock
90 Lock a user's password. This puts a '!' in front of the encrypted
91 password, effectively disabling the password. You can't use this
92 option with -p or -U.
93 Note: if you wish to lock the account (not only access with a
95 password), you should also set the EXPIRE_DATE to 1.
96 -m, --move-home
98 Move the content of the user's home directory to the new location.
99 If the current home directory does not exist the new home directory
100 will not be created.
101 This option is only valid in combination with the -d (or --home)
103 option.
104 usermod will try to adapt the ownership of the files and to copy
106 the modes, ACL and extended attributes, but manual changes might be
107 needed afterwards.
108 -o, --non-unique
110 When used with the -u option, this option allows to change the user
111 ID to a non-unique value.
112 -p, --password PASSWORD
114 The encrypted password, as returned by crypt(3).
115 Note: This option is not recommended because the password (or
117 encrypted password) will be visible by users listing the processes.
118 You should make sure the password respects the system's password
120 policy.
121 -R, --root CHROOT_DIR
123 Apply changes in the CHROOT_DIR directory and use the configuration
124 files from the CHROOT_DIR directory.
125 -P, --prefix PREFIX_DIR
127 Apply changes in the PREFIX_DIR directory and use the configuration
128 files from the PREFIX_DIR directory. This option does not chroot
129 and is intended for preparing a cross-compilation target. Some
130 limitations: NIS and LDAP users/groups are not verified. PAM
131 authentication is using the host files. No SELINUX support.
132 -s, --shell SHELL
134 The path of the user's new login shell. Setting this field to blank
135 causes the system to select the default login shell.
136 -u, --uid UID
138 The new numerical value of the user's ID.
139 This value must be unique, unless the -o option is used. The value
141 must be non-negative.
142 The user's mailbox, and any files which the user owns and which are
144 located in the user's home directory will have the file user ID
145 changed automatically.
146 The ownership of files outside of the user's home directory must be
148 fixed manually.
149 The change of the user ownership of files inside of the user's home
151 directory is also not done if the home dir owner uid is different
152 from the current or new user id. This is a safety measure for
153 special home directories such as /.
154 No checks will be performed with regard to the UID_MIN, UID_MAX,
156 SYS_UID_MIN, or SYS_UID_MAX from /etc/login.defs.
157 -U, --unlock
159 Unlock a user's password. This removes the '!' in front of the
160 encrypted password. You can't use this option with -p or -L.
161 Note: if you wish to unlock the account (not only access with a
163 password), you should also set the EXPIRE_DATE (for example to
164 99999, or to the EXPIRE value from /etc/default/useradd).
165 -v, --add-subuids FIRST-LAST
167 Add a range of subordinate uids to the user's account.
168 This option may be specified multiple times to add multiple ranges
170 to a users account.
171 No checks will be performed with regard to SUB_UID_MIN,
173 SUB_UID_MAX, or SUB_UID_COUNT from /etc/login.defs.
174 -V, --del-subuids FIRST-LAST
176 Remove a range of subordinate uids from the user's account.
177 This option may be specified multiple times to remove multiple
179 ranges to a users account. When both --del-subuids and
180 --add-subuids are specified, the removal of all subordinate uid
181 ranges happens before any subordinate uid range is added.
182 No checks will be performed with regard to SUB_UID_MIN,
184 SUB_UID_MAX, or SUB_UID_COUNT from /etc/login.defs.
185 -w, --add-subgids FIRST-LAST
187 Add a range of subordinate gids to the user's account.
188 This option may be specified multiple times to add multiple ranges
190 to a users account.
191 No checks will be performed with regard to SUB_GID_MIN,
193 SUB_GID_MAX, or SUB_GID_COUNT from /etc/login.defs.
194 -W, --del-subgids FIRST-LAST
196 Remove a range of subordinate gids from the user's account.
197 This option may be specified multiple times to remove multiple
199 ranges to a users account. When both --del-subgids and
200 --add-subgids are specified, the removal of all subordinate gid
201 ranges happens before any subordinate gid range is added.
202 No checks will be performed with regard to SUB_GID_MIN,
204 SUB_GID_MAX, or SUB_GID_COUNT from /etc/login.defs.
205 -Z, --selinux-user SEUSER
207 The new SELinux user for the user's login.
208 A blank SEUSER will remove the SELinux user mapping for user LOGIN
210 (if any).
211
213 You must make certain that the named user is not executing any
214 processes when this command is being executed if the user's numerical
215 user ID, the user's name, or the user's home directory is being
216 changed. usermod checks this on Linux. On other platforms it only uses
217 utmp to check if the user is logged in.
218 You must change the owner of any crontab files or at jobs manually.
220 You must make any changes involving NIS on the NIS server.
222
224 The following configuration variables in /etc/login.defs change the
225 behavior of this tool:
226 LASTLOG_UID_MAX (number)
228 Highest user ID number for which the lastlog entries should be
229 updated. As higher user IDs are usually tracked by remote user
230 identity and authentication services there is no need to create a
231 huge sparse lastlog file for them.
232 No LASTLOG_UID_MAX option present in the configuration means that
234 there is no user ID limit for writing lastlog entries.
235 MAIL_DIR (string)
237 The mail spool directory. This is needed to manipulate the mailbox
238 when its corresponding user account is modified or deleted. If not
239 specified, a compile-time default is used.
240 MAIL_FILE (string)
242 Defines the location of the users mail spool files relatively to
243 their home directory.
244 The MAIL_DIR and MAIL_FILE variables are used by useradd, usermod, and
246 userdel to create, move, or delete the user's mail spool.
247 If MAIL_CHECK_ENAB is set to yes, they are also used to define the MAIL
249 environment variable.
250 MAX_MEMBERS_PER_GROUP (number)
252 Maximum members per group entry. When the maximum is reached, a new
253 group entry (line) is started in /etc/group (with the same name,
254 same password, and same GID).
255 The default value is 0, meaning that there are no limits in the
257 number of members in a group.
258 This feature (split group) permits to limit the length of lines in
260 the group file. This is useful to make sure that lines for NIS
261 groups are not larger than 1024 characters.
262 If you need to enforce such limit, you can use 25.
264 Note: split groups may not be supported by all tools (even in the
266 Shadow toolsuite). You should not use this variable unless you
267 really need it.
268 SUB_GID_MIN (number), SUB_GID_MAX (number), SUB_GID_COUNT (number)
270 If /etc/subuid exists, the commands useradd and newusers (unless
271 the user already have subordinate group IDs) allocate SUB_GID_COUNT
272 unused group IDs from the range SUB_GID_MIN to SUB_GID_MAX for each
273 new user.
274 The default values for SUB_GID_MIN, SUB_GID_MAX, SUB_GID_COUNT are
276 respectively 100000, 600100000 and 65536.
277 SUB_UID_MIN (number), SUB_UID_MAX (number), SUB_UID_COUNT (number)
279 If /etc/subuid exists, the commands useradd and newusers (unless
280 the user already have subordinate user IDs) allocate SUB_UID_COUNT
281 unused user IDs from the range SUB_UID_MIN to SUB_UID_MAX for each
282 new user.
283 The default values for SUB_UID_MIN, SUB_UID_MAX, SUB_UID_COUNT are
285 respectively 100000, 600100000 and 65536.
286
288 /etc/group
289 Group account information.
290 /etc/gshadow
292 Secure group account information.
293 /etc/login.defs
295 Shadow password suite configuration.
296 /etc/passwd
298 User account information.
299 /etc/shadow
301 Secure user account information.
302 /etc/subgid
304 Per user subordinate group IDs.
305 /etc/subuid
307 Per user subordinate user IDs.
308
310 chfn(1), chsh(1), passwd(1), crypt(3), gpasswd(8), groupadd(8),
311 groupdel(8), groupmod(8), login.defs(5), subgid(5), subuid(5),
312 useradd(8), userdel(8).
313shadow-utils 4.9 11/19/2021 USERMOD(8)