Linux chfn command
chfn(Change Finger Information) is a command-line tool in Linux used to modify a user's personal description information.
chfnThe command is used to modify the user's finger information in the system, including full name, office address, office phone, home phone, etc.
This information can befingerviewed by other users using the command, making it convenient to know each other's contact information in a multi-user collaborative server environment.
In early Unix systems,
fingerthe command could view detailed user information,chfnand provides an entry point to modify this information.Although
fingerthe frequency of use in modern systems has decreased, butchfnthe GECOS field managed by it is still used by many programs as the source of the user's display name.The GECOS field is
/etc/passwdthe 5th colon-separated field in the file, storing the user's description information.chfnEssentially, it is modifying this field.
Command syntax
chfnThe basic syntax is as follows:
chfn [选项] [用户名]
If no username is specified, the information of the currently logged-in user is modified by default.
Ordinary users can only modify their own information, while the root user can modify any user's information.
Options description
chfnThe common options are listed as follows:
| Option | Description | Example |
|---|---|---|
-f, --full-name | Set the user's full name | chfn -f "Zhang San" |
-r, --room | Set the office room number | chfn -r "A-301" |
-w, --work-phone | Set the work phone number | chfn -w "010-12345678" |
-h, --home-phone | Set the home phone number | chfn -h "010-87654321" |
-o, --other | Set other information (Other, the rest of the GECOS field) | chfn -o "Developer" |
-u, --help | Display help information | chfn -u |
Detailed usage
Modify personal information interactively
Run without any optionschfnwill prompt the user to input item by item interactively:
# 交互式修改当前用户信息
$ chfn
Password:
Changing the user information for example
Enter the new value, or press ENTER for the default
Full Name: example
Room Number []: A-301
Work Phone []: 010-12345678
Home Phone []: 010-87654321
Each prompt line displays the current value. If you don't want to modify a certain item, just press Enter to skip it.
The system will first require password verification to ensure that only the user themselves or root can modify.
Modify directly using options
In scripts or batch operations, you can use options to skip interactive prompts and directly specify new values:
# 一次性设置用户全名和办公室号码 $ chfn -f "Li Si" -r "B-202" example
After execution, the userexample's full name will be set to "Li Si", and office number to "B-202".
View the modified information
After the modification is complete, you can usefingercommand to view the updated information:
# 使用 finger 查看用户信息 $ finger example Login: example Name: Li Si Directory: /home/example Shell: /bin/bash Office: B-202, 010-12345678 Home Phone: 010-87654321 Last login Tue May 19 10:30 (CST) on pts/0 No mail. No Plan.
If the system does not have
fingerinstalled, you can usegetent passwd exampleto directly view/etc/passwdthe GECOS field in
Verify by directly reading /etc/passwd
The parts in the GECOS field are separated by commas, with the format:Full name, Office, Work phone, Home phone, Other。
# 查看 /etc/passwd 中 example 用户的 GECOS 字段 $ grep example /etc/passwd example:x:1001:1001:Li Si,B-202,010-12345678,010-87654321:/home/example:/bin/bash
It can be seen that the GECOS field (the 5th colon-separated content) completely records all the information just set.
Modify a single item
You can modify only one item while keeping other information unchanged:
# 只修改全名，其他信息保持不变 $ chfn -f "Wang Wu" example # 验证修改结果 $ finger example | grep Name Login: example Name: Wang Wu
chfn configuration file
chfnThe behavior is controlled by/etc/login.defsthe configuration in:
| Configuration item | Description | Default value |
|---|---|---|
CHFN_RESTRICT | Restricts the fields that can be modified, using a combination of letters:f(full name),r(room),w(work phone),h(home phone) | frwh |
If set to an empty string, no user is allowed to modify finger information.
System administrators can control which fields users can modify by adjusting this configuration.
Notes
Ordinary users can only modify their own finger information and need to provide their current password for verification. The root user can modify any user's information without password verification.
chfnThe modified information will be written to/etc/passwdIncorrect modifications may cause some programs that depend on the GECOS field to display abnormally. It is recommended to back up the relevant lines before modifying.
If the system disableschfnthe function (CHFN_RESTRICTis empty), running this command will prompt insufficient permissions.
Some modern Linux distributions (such as Ubuntu) do not installfingerpackage by default; you need to manually runapt install fingerto install.
In centralized authentication environments such as LDAP or NIS,chfnmay not work properly; in such environments, the corresponding management tools should be used.
Related commands
| Command | Description |
|---|---|
finger | View a user's finger information |
chsh | Modify a user's default login shell |
chage | Modify user password expiration information |
usermod | Modify various attributes of a user account (including the GECOS field) |
passwd | Modify a user's password |
getent | Retrieve entry information from system databases |