passwd ‐ #security #users - five4nets/Linux-Knowledgebase GitHub Wiki
🔐 Linux passwd Command Tutorial
The passwd command in Linux is used to change user account passwords and manage password policies. It's a vital tool for both users and system administrators to maintain system security.
🧰 Basic Syntax
passwd [OPTIONS] [USERNAME]
- USERNAME: The target user account. If omitted, it defaults to the current user.
- OPTIONS: Flags to modify behavior (e.g., lock, expire, status).
🔧 Common Options
| Option | Description |
|---|---|
-d |
Delete a user's password (makes account passwordless) |
-e |
Expire a password immediately (forces change at next login) |
-l |
Lock a user account |
-u |
Unlock a user account |
-S |
Show password status |
-n |
Set minimum days between password changes |
-x |
Set maximum days a password is valid |
-w |
Set warning days before password expiration |
-i |
Set days of inactivity after password expiration |
-a |
Show status for all users (used with -S) |
🧪 Examples
1. Change Your Own Password
passwd
2. Change Another User's Password (as root)
sudo passwd username
3. Lock a User Account
sudo passwd -l username
4. Unlock a User Account
sudo passwd -u username
5. Expire a Password Immediately
sudo passwd -e username
6. Delete a User's Password
sudo passwd -d username
7. View Password Status
passwd -S username
8. Set Password Expiry Policy
sudo passwd -n 1 -x 90 -w 7 username
This sets:
- Minimum days between changes: 1
- Maximum password age: 90 days
- Warning period: 7 days
🧠 Notes
- Passwords are stored in encrypted form in
/etc/shadow. - When typing passwords, no characters are shown for security.
- Locked accounts cannot be accessed via password but may still allow SSH key login.
📚 References
- Linux Handbook: passwd command examples
- GeeksforGeeks: passwd command in Linux
- Baeldung: Guide to passwd command
- man7.org: passwd manual page
Happy securing! 🔐
Let me know if you'd like a version that includes password aging policies or integrates with `chage` for advanced control.