The `-e` flag with the Linux passwd command forces a user to change their password at next login. If you’ve ever wondered what flag can be used in linux with the passwd command to force a user to change their password, the answer is straightforward: the `-e` option. This simple yet powerful flag immediately expires a user’s password, compelling them to set a new one upon their next authentication attempt.
In this guide, you’ll learn exactly how to use the `-e` flag, see practical examples, and understand its role in system security. We’ll cover everything from basic usage to advanced scenarios, so you can confidently manage password policies on your Linux system.
What Flag Can Be Used In Linux With The Passwd Command To Force A User To Change Their Password
The flag you need is `-e` (short for “expire”). When you run `passwd -e username`, it marks the user’s password as expired. The next time that user logs in, the system forces them to choose a new password before granting access.
This is different from locking an account or resetting a password. The `-e` flag doesn’t change the current password—it simply invalidates it for future logins. The user must create a new password that meets your system’s password policy requirements.
How The -E Flag Works Technically
Behind the scenes, the `-e` flag sets the password’s last change date to 0 (the epoch). This makes the password appear as if it was last changed on January 1, 1970. Since most systems have a maximum password age setting, this forces an immediate change.
The `/etc/shadow` file stores this information. After running `passwd -e`, the third field (last password change) becomes 0. You can verify this with:
sudo cat /etc/shadow | grep username- Look for the third colon-separated field
- If it shows 0, the password is expired
Prerequisites For Using The -E Flag
Before you can force a password change, you need:
- Root or sudo privileges on the Linux system
- The username of the target account
- Basic familiarity with the terminal
- A password policy configured (optional but recommended)
Without root access, you cannot expire another user’s password. Regular users can only change their own password, not force changes on others.
Step-By-Step Guide: Using Passwd -E
Let’s walk through the exact steps to force a password change using the `-e` flag. Follow along on your own system to see it in action.
Step 1: Open A Terminal
Launch your terminal emulator. On most Linux distributions, you can press Ctrl+Alt+T or search for “Terminal” in your applications menu.
Step 2: Check Current Password Status
Before expiring the password, see the current state:
sudo chage -l username
This shows the last password change date, expiry info, and other details. Note the “Last password change” field for comparison.
Step 3: Expire The Password
Run the command with the `-e` flag:
sudo passwd -e username
Replace “username” with the actual account name. You’ll see output like:
passwd: password expiry information changed.
Step 4: Verify The Change
Check that the password is now expired:
sudo chage -l username
The “Last password change” field should now show “password must be changed” or a date in the past.
Step 5: Test The Forced Change
Log out and try logging in as that user. The system will prompt:
You are required to change your password immediately (root enforced)
Then it will ask for the current password (the old one), followed by the new password twice.
Common Use Cases For The -E Flag
The `-e` flag is useful in several real-world scenarios. Here are the most common situations where you’d want to force a password change.
New User Accounts
When creating a new user, you might set a temporary password and then expire it. This ensures the user chooses their own password on first login. For example:
- Create user:
sudo useradd -m newuser - Set temp password:
sudo passwd newuser - Expire it:
sudo passwd -e newuser
This workflow is standard for onboarding new employees or granting access to guest accounts.
Security Incidents
If you suspect a user’s password has been compromised, immediately expire it. This forces them to change credentials before they can access the system again. Combine this with account locking if needed:
sudo usermod -L username (lock account)
sudo passwd -e username (expire password)
sudo usermod -U username (unlock after user contacts admin)
Password Policy Enforcement
You can use `-e` as part of a broader password rotation policy. For example, if your company requires password changes every 90 days, you can manually expire passwords for users who haven’t changed theirs in time.
Audit And Compliance
During security audits, you may need to demonstrate that users are forced to change passwords regularly. The `-e` flag helps you enforce this on demand.
Alternative Methods To Force Password Changes
While `-e` is the direct flag, there are other ways to achieve the same result. Each method has its own advantages.
Using The Chage Command
The chage command offers more granular control. To force a password change:
sudo chage -d 0 username
This sets the last password change date to 0, same effect as `passwd -e`. The -d option stands for “last day.”
Editing /Etc/Shadow Directly
For advanced users, you can edit the shadow file manually:
sudo vipw -s
Find the user’s line and change the third field (colon-separated) to 0. Save and exit. This is risky and not recommended for beginners.
Using A Script
For bulk operations, create a script:
for user in user1 user2 user3; do sudo passwd -e $user; done
This expires passwords for multiple users at once. Useful for mass password resets.
Important Considerations And Warnings
Using the `-e` flag is powerful but comes with responsibilities. Keep these points in mind.
User Experience Impact
Forcing a password change can be frustrating for users. Always communicate with them beforehand if possible. Explain why the change is necessary and provide instructions for setting a strong password.
Password History
If your system has password history enabled, users cannot reuse recent passwords. The `-e` flag respects these settings. Check your PAM configuration for details.
Root Account
You cannot force the root user to change their password using `-e` while logged in as root. The root account is exempt from password expiration by design. To change root’s password, use sudo passwd root.
Service Accounts
Be careful with service accounts (like www-data or mysql). Expiring their password can break automated processes. Only force changes on human user accounts.
SSH Key Authentication
If a user logs in via SSH keys, they may not be prompted for a password change. The `-e` flag only affects password-based authentication. Users with key-based access might bypass the forced change.
Troubleshooting Common Issues
Even with the correct flag, you might encounter problems. Here’s how to handle them.
User Cannot Change Password
If the user gets an error like “You are not allowed to change your password,” check:
- Password aging settings:
sudo chage -l username - Account lock status:
sudo passwd -S username - PAM configuration in /etc/pam.d/
Password Change Not Prompted
If the user logs in without being forced to change, verify:
- The `-e` flag was applied correctly
- The user is logging in via password, not SSH keys
- No other authentication methods are bypassing the check
System Doesn’t Accept New Password
If the user’s new password is rejected, check password policy:
- Minimum length:
grep pam_passwdqc /etc/pam.d/common-password - Complexity requirements
- Dictionary checks
Best Practices For Password Management
Using the `-e` flag is just one part of a solid password strategy. Follow these best practices for better security.
Set Password Expiration Policies
Instead of manually expiring passwords, configure automatic expiration:
sudo chage -M 90 username (max days)
sudo chage -m 7 username (min days)
sudo chage -W 7 username (warning days)
This enforces regular changes without manual intervention.
Use Strong Password Requirements
Configure PAM to enforce complexity:
- Minimum 12 characters
- Mix of uppercase, lowercase, digits, symbols
- No dictionary words
- No personal information
Implement Multi-Factor Authentication
Passwords alone aren’t enough. Consider adding MFA for critical systems. Tools like Google Authenticator or YubiKey can supplement password security.
Monitor For Weak Passwords
Regularly audit user passwords using tools like john or hashcat (on your own systems only). Identify and force changes for weak passwords.
Frequently Asked Questions
What Flag Forces A Password Change In Linux?
The `-e` flag with the passwd command forces a user to change their password at next login. For example: sudo passwd -e username.
Can I Force A Password Change For Multiple Users At Once?
Yes, use a loop in bash: for user in user1 user2 user3; do sudo passwd -e $user; done. This expires passwords for all listed users.
Does The -E Flag Work For The Root User?
No, the root account is exempt from password expiration. You cannot force root to change password using `-e`. Use sudo passwd root to change it directly.
What Happens If I Expire A Password For A Service Account?
Service accounts may stop working if their password is expired. Automated processes that rely on password authentication will fail. Only expire passwords for human users.
How Do I Undo A Forced Password Change?
Set the password’s last change date to today: sudo chage -d $(date +%Y-%m-%d) username. This removes the expiration and allows the user to keep their current password.
Conclusion
The `-e` flag with the Linux passwd command is the direct answer to what flag can be used in linux with the passwd command to force a user to change their password. It’s a simple, effective tool for managing password security on any Linux system.
Remember to use this flag responsibly. Communicate with users before forcing changes, and combine it with proper password policies for maximum security. Whether you’re onboarding new users, responding to security incidents, or enforcing compliance, the `-e` flag gives you precise control over password expiration.
Practice the commands on a test system first. Once you’re comfortable, you’ll find this flag invaluable for maintaining a secure Linux environment. Your users will appreciate the forced change when they understand it protects their accounts and the entire system.