There are three main situations for modifying Linux passwords: 1. Modify the current user password, use the passwd command, enter the original password and set a new password; 2. The administrator changes other user passwords, uses the sudo passwd user name, and directly sets a new password; 3. When forgetting your password, reset it through single-user mode, restart and enter the GRUB menu to select recovery mode, and use passwd to modify it under the root shell. Note that the password should be complicated and changed regularly to avoid affecting the system account. Pay attention to permissions and security policies when operating.
Changing passwords is actually not difficult in Linux, but many people tend to get stuck in commands or permissions when they operate for the first time. Simply put, you only need to use the passwd
command and pay attention to permissions and system types.

Modify the current user's password
This is the most common requirement, such as remembering your login password and wanting to change to a more secure one. The operation is very simple:
- Enter the command:
passwd
- The system will first ask you to enter the current password to verify your identity
- Then you will enter the new password twice
Note that characters will not be displayed on the screen when entering a password, which is a normal security mechanism. If you enter the current password incorrectly, the system will refuse to modify it. New passwords should be as complex as possible, such as including uppercase and uppercase letters, numbers and symbols.

Modify the password of other users (root permission is required)
If you are an administrator and want to change someone else's password, you need to use sudo
or log in as root.
- Use the command:
sudo passwd 用戶名
- Then enter the new password you want to set
For example, if you want to change the password of the user testuser
, enter:

sudo passwd testuser
At this time, you don’t need to know the other party’s original password, just set the new password. But be careful and don't mistakenly change the password of the system account, such as root
or daemon
, which may affect the system operation.
Modify password without password (single user mode)
Sometimes you forget your password, or you are a newly acquired system and want to reset your password, you can enter single-user mode.
- Restart the system
- Hold down
Shift
key (BIOS) orEsc
(UEFI) at startup to bring up the GRUB menu - Select "Advanced options", then select "recovery mode" or similar options
- After entering, select "Drop to root shell prompt"
- Enter the command:
mount -o remount,rw /
(Some systems are read-only by default) - Then use
passwd 用戶名
to modify the password
After completion, enter reboot
and restart the system. This method is suitable for most mainstream Linux distributions, such as Ubuntu, Debian, CentOS, etc.
Password Policy and Security Recommendations
- Password complexity : It is recommended to include at least 8 digits, including upper and lower case numeric symbols
- Regular replacement : Especially for server accounts, it is recommended to change them every 3 to 6 months
- Do not reuse passwords : try to be different between different systems
- Using password managers : such as KeePassXC, you can safely store and generate passwords
In addition, some systems will limit the frequency of password modification, such as not being able to change it immediately after it has been modified, which is for security reasons.
Basically that's it. It is not complicated to change passwords on Linux, but you need to pay attention to permissions and operation methods. Just don’t change the password of your system account randomly.
The above is the detailed content of how to change password in linux. For more information, please follow other related articles on the PHP Chinese website!

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