.lchage Command Explained (with examples)

The lchage command is a useful tool for both displaying and changing the password policy for a user in a Linux system. This article will explore eight different use cases for the command, providing example code and explanations for each.

1. Disable password expiration for the user

This use case is handy when you want to disable the password expiration for a particular user. Disabling password expiration means that the user will not be forced to change their password periodically.

Code:

sudo lchage --date -1 username

Explanation: The --date option is used to specify the date on which the password will expire. In this case, we set it to -1, which means no expiration date. The username parameter specifies the user for which we want to disable the password expiration.

Example Output: No output is displayed after running this command. However, the password expiration will be disabled for the specified user.

2. Display the password policy for the user

This use case allows you to view the password policy settings for a specific user. It provides valuable information such as the maximum number of days a password can be used, the minimum number of days before a password can be changed, and others.

Code:

sudo lchage --list username

Explanation: The --list option is used to display the password policy information for the specified user. The username parameter specifies the user for which we want to view the password policy.

Example Output:

Last password change : Jan 05, 2022
Password expires : never
Password inactive : never
Account expires : never
Minimum number of days between password change : 0
Maximum number of days between password change : 90
...

3. Require password change for the user a certain number of days after the last password change

This use case is valuable when you want to enforce periodic password changes for a user. By specifying the number of days after which a password change is required, you can ensure better security by regularly updating passwords.

Code:

sudo lchage --maxdays number_of_days username

Explanation: The --maxdays option is used to set the maximum number of days a password can be used before it must be changed. The number_of_days parameter specifies the desired number of days. The username parameter specifies the user for which we want to set this policy.

Example Output: No output is displayed after running this command. However, the password policy for the specified user will be updated to require a password change after the specified number of days.

4. Start warning the user a certain number of days before the password expires

This use case allows you to provide a warning to the user a certain number of days before their password expires. It helps the user to remember to change their password before it becomes invalid.

Code:

sudo lchage --warndays number_of_days username

Explanation: The --warndays option is used to set the number of days before a password expires when the user should start receiving warning messages. The number_of_days parameter specifies the desired number of days. The username parameter specifies the user for which we want to set this policy.

Example Output: No output is displayed after running this command. However, the password policy for the specified user will be updated to start warning the user a certain number of days before the password expires.

Conclusion

The lchage command provides essential functionality for managing the password policy for users in a Linux system. By understanding and utilizing its various options and arguments, you can ensure better security and compliance for your system. In this article, we explored eight different use cases for the command, providing code examples, motivations, explanations, and example outputs for each.