passwd Command Cheat Sheet

passwd allows users to change their account passwords and allows administrators to manage password policies.

Synopsis

passwd [options] [LOGIN]

Changing Passwords

Change Your Own Password

passwd

Change Another User's Password (Root)

sudo passwd username

Force Password Change on Next Login (-e)

Expire the password immediately.

sudo passwd -e username

Locking & Unlocking

Lock Account (-l)

Prevents the user from logging in via password. (Does not prevent SSH Key login!).

sudo passwd -l username

Unlock Account (-u)

sudo passwd -u username

Status & Info

Check Account Status (-S)

Displays status code: - P: Usable password. - L: Locked. - NP: No password.

sudo passwd -S username
# Output: alice P 01/01/2024 0 99999 7 -1

Password Aging (Policies)

Set persistent rules for a user.

Set Minimum/Maximum Days

• Minimum days between changes (-n).
• Maximum days valid (-x).
• Warning days before expiry (-w).

# Must wait 10 days to change again. Expire in 90 days. Warn 7 days before.
sudo passwd -n 10 -x 90 -w 7 username

Advanced: Pipe Input

Common in automation scripts to set password non-interactively. Warning: Only use this in secure environments (command history logs might capture it).

echo "username:newpassword" | sudo chpasswd

If you MUST pipe to passwd:

echo "newpassword" | sudo passwd --stdin username

Notes

• File: passwd updates /etc/shadow (secure), not /etc/passwd.
• Delete Password: passwd -d username allows login without a password (very insecure).