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This article mainly explains "introduction to the usage of passwd commands in Linux system". The explanation in this article is simple and clear, and is easy to learn and understand. Please follow the editor's train of thought to study and learn "introduction to the usage of passwd commands in Linux system".

Let's review the basic usage of the passwd command:

The Linux passwd command is used to change the user's password

Grammar

Passwd [- k] [- l] [- u [- f]] [- d] [- S] [username]

Required parameters:

-d delete password

-f Enforcement

-k updates can only be sent after expiration

-l stop using the account

-S displays password information

-u enable accounts that have been stopped

-x set the period of validity of the password

-g modify group password

-I stop the user account after expiration

Select parameters:

-- help displays help information

-- version displays version information

Example

Modify a user's password

The code is as follows:

# passwd w3cschool / / set the password of the w3cschool user

Enter new UNIX password: / / enter a new password. The password entered has no echo.

Retype new UNIX password: / / confirm password

Passwd: password updated successfully

#

Display account password information

The code is as follows:

# passwd-S w3cschool

W3cschool P 05Compact 13 Compact 2010 0 99999 7-1

Delete user password

The code is as follows:

# passwd-d lx138

Passwd: password expiry information changed.

OK, let's take a look at the actual application:

Example 1: change the password of a system user

When you log in with a non-root user, such as when I log in with 'linuxtechi', running the passwd command resets the password of the current logged-in user.

The code is as follows:

[linuxtechi@linuxworld ~] $passwd

Changing password for user linuxtechi.

Changing password for linuxtechi.

(current) UNIX password:

New password:

Retype new password:

Passwd: all authentication tokens updated successfully.

[linuxtechi@linuxworld ~] $

When you log in as a root user and run the passwd command, it resets root's password by default, and if you specify a user name after the passwd command, it resets that user's password.

The code is as follows:

[root@linuxworld ~] # passwd

[root@linuxworld ~] # passwd linuxtechi

Note: the password of the system user is stored in the / etc/shadow file in encrypted form.

Example 2: display password status information

To display the status information of the user's password, use the-S option after the passwd command.

The code is as follows:

[root@linuxworld] # passwd-S linuxtechi

Linuxtechi PS 2015-09-200 99999 7-1 (Password set, SHA512 crypt.)

[root@linuxworld ~] #

In the above output, the first field shows the user name, the second field shows the password status (PS = password setting, LK = password locked, NP = no password), the third field shows the time when the password was last modified, and the next four fields show the minimum and maximum period for which the password can be changed, the warning period, and the length of time the password has not been used.

Example 3: display the password status information of all accounts

In order to display status information for all user passwords, you need to use the "- aS" option in the passwd command, the example is as follows:

The code is as follows:

Root@localhost:~# passwd-Sa

LCTT Note: different distributions / passwd behave differently. CentOS6.6 did not test successfully, but Ubuntu can.)

Example 4: delete a user's password using the-d option

Use me as an example to delete the password of the 'linuxtechi' user.

The code is as follows:

[root@linuxworld] # passwd-d linuxtechi

Removing password for user linuxtechi.

Passwd: Success

[root@linuxworld ~] #

[root@linuxworld] # passwd-S linuxtechi

Linuxtechi NP 2015-09-200 99999 7-1 (Empty password.)

[root@linuxworld ~] #

The "- d" option clears the user's password and disables user login.

Example 5: set the password to expire immediately

Using the'- e' option in the passwd command immediately causes the user's password to expire, which forces the user to change the password the next time they log in.

The code is as follows:

[root@linuxworld] # passwd-e linuxtechi

Expiring password for user linuxtechi.

Passwd: Success

[root@linuxworld] # passwd-S linuxtechi

Linuxtechi PS 1970-01-01 99999 7-1 (Password set, SHA512 crypt.)

[root@linuxworld ~] #

Now try to connect to the host using linuxtechi user SSH.

Example 6: lock the password of a system user

Use the'- l 'option in the passwd command to lock the user's password, which adds "!" to the beginning of the password. When his / her password is locked, the user will not be able to change its password.

The code is as follows:

[root@linuxworld ~] # passwd-l linuxtechi

Locking password for user linuxtechi.

Passwd: Success

[root@linuxworld] # passwd-S linuxtechi

Linuxtechi LK 2015-09-200 99999 7-1 (Password locked.)

[root@linuxworld ~] #

Example 7: use the-u option to unlock the user password

The code is as follows:

[root@linuxworld] # passwd-u linuxtechi

Unlocking password for user linuxtechi.

Passwd: Success

[root@linuxworld ~] #

Example 8: use the-I option to set inactivity time

Use the-I option in the passwd command to set the inactivity time of the system user. When the password of the user (I am using the linuxtechi user) expires and the user does not change his password after another'n 'day (10 days in my case), the user will not be able to log in.

The code is as follows:

[root@linuxworld] # passwd-I 10 linuxtechi

Adjusting aging data for user linuxtechi.

Passwd: Success

[root@linuxworld ~] #

[root@linuxworld] # passwd-S linuxtechi

Linuxtechi PS 2015-09-200 99999 7 10 (Password set, SHA512 crypt.)

[root@linuxworld ~] #

Example 9: use the-n option to set the minimum time for password change

In the following example, the linuxtechi user must change the password within 90 days. 0 means that the user can change its password at any time.

The code is as follows:

[root@linuxworld] # passwd-n 90 linuxtechi

Adjusting aging data for user linuxtechi.

Passwd: Success

[root@linuxworld] # passwd-S linuxtechi

Linuxtechi PS 2015-09-20 90 99999 7 10 (Password set, SHA512 crypt.)

[root@linuxworld ~] #

Example 10: use the-w option to set the warning period before the password expires

The'- w 'option is used to set the warning period for the user in the passwd command. This means that his / her password will expire after n days.

The code is as follows:

[root@linuxworld] # passwd-w 12 linuxtechi

Adjusting aging data for user linuxtechi.

Passwd: Success

[root@linuxworld] # passwd-S linuxtechi

Linuxtechi PS 2015-09-20 90 99999 12 10 (Password set, SHA512 crypt.)

[root@linuxworld ~] #

Thank you for your reading. the above is the content of "introduction of passwd command usage in Linux system". After the study of this article, I believe you have a deeper understanding of the introduction of passwd command usage in Linux system, and the specific use needs to be verified in practice. Here is, the editor will push for you more related knowledge points of the article, welcome to follow!

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