The chage command Examples and Usages

The chage command updates password aging information. Password aging is a set of options administrators use to secure user passwords. The /etc/shadow file saves user passwords and password aging information on a standalone Linux system.

The chage command syntax

The chage command uses the following syntax.

#chage [options] username

The chage command options

The following table lists the chage command options and their meaning.

The chage command examples

The following are common usages of the chage command.

Listing aging information

The -l option lists the password aging information. The following command lists the password aging values of rheluser.

#chage -l rheluser

Using interactive prompt to manage password aging information

If we run the chage command without any option, it starts in the interactive mode. In interactive mode, it lists the value of each aging option and allows us to update or keep it. The following image shows an example of the interactive mode.

Changing the last password change date

The -d (--lastday) option sets the last password change date in the number of days. It accepts the argument in the date format (YYYY-MM-DD). It converts the given date into the number of days. The following command sets the last password change date to 10 August 2024.

#chage –d 2024-08-10 rheluser

Forcing the user to change his password at the next login

If we provide 0 (zero) as the argument with the -d option, it forces the user to change his password on the next log-on. The following command forces the user to change his password on the next log-on.

#chage –d 0 rheluser

Changing account lockout days

The -I option sets the number of days after the system locks the user account if the user does not change his expired password. The following command changes the password inactive days to 5 days.

#chage –I 5 rheluser

The value -1 with this option resets the password inactive days back to the default value.

Displaying a warning message before the password expires

The -W option sets the number of days earlier the user will get the warning message to change his password before the password expires. For example, The following command sets the warning message days to 5 days before the password expires.

#chage –W 5 rheluser

The chage command help options

If you need help with the chage command, use the -h or --help option. When used with this option, it lists a summary of all options and their usage.

If you need a detailed overview of this command and all options, use its manual pages. The following command displays the manual of this command.

The chage command exit codes

The following table lists the exit code of the chage command.

The chage command configuration files

The chage command depends on the following configuration files.

The /etc/login.defs file

This file defines the default configuration values for various login parameters. These parameters include the options that the chage command updates. The chage command uses this file to select the default values of related parameters.

The /etc/default/useradd

The chage command updates the values the useradd command sets. The useradd command picks default values from this file.

The /etc/shadow file

This file saves all the values the chage command updates.

Conclusion

By understanding the chage command, you can effectively manage password aging information and enhance the security of user passwords on Linux systems. Mastering the chage command is essential for maintaining a secure and well-managed Linux environment. This tutorial presented a detailed overview of the chage command and its options. It also explained common usages of this command through examples.