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chpasswd

user managementLinux
The chpasswd command is one of the most frequently used commands in Linux/Unix-like operating systems. chpasswd Update passwords in batch mode
See ExamplesView Syntax

Quick Reference

Command Name:

chpasswd

Category:

user management

Platform:

Linux

Basic Usage:

chpasswd [options] [arguments]

Common Use Cases

    Syntax

    chpasswd [options]

    Options

    Option Description
    -c, --crypt-method METHOD Use the specified method to encrypt the passwords (DES, MD5, NONE, SHA256, SHA512)
    -e, --encrypted Supplied passwords are already encrypted
    -m, --md5 Use MD5 encryption instead of DES
    -R, --root CHROOT_DIR Directory to chroot into
    -s, --sha-rounds ROUNDS Number of SHA rounds for the SHA256/SHA512 crypt algorithms
    -h, --help Display help message and exit

    Examples

    How to Use These Examples

    The examples below show common ways to use the chpasswd command. Try them in your terminal to see the results. You can copy any example by clicking on the code block.

    #

    Basic Examples:

    # Change passwords for multiple users using a file
echo "user1:newpassword1
user2:newpassword2
user3:newpassword3" | sudo chpasswd
    # Change passwords with encryption specified echo "user1:newpassword1" | sudo chpasswd -e
    # Use a specific encryption method echo "user1:newpassword1" | sudo chpasswd -c SHA512
    # Read user/password pairs from a file sudo chpasswd < user_passwords.txt

    Advanced Examples:

    # Change password for a single user with MD5 encryption
echo "user1:newpassword1" | sudo chpasswd -m
    # Use with a script to update many accounts 
    cat /path/to/userlist.txt | sudo chpasswd
    # Create a password update script #!/bin/bash # Generate password file for user in $(cat userlist.txt); do echo "$user:$(openssl rand -base64 12)" >> passwords.txt done # Update passwords sudo chpasswd < passwords.txt

    Try It Yourself

    Practice makes perfect! The best way to learn is by trying these examples on your own system with real files.

    Understanding Syntax

    Pay attention to the syntax coloring: commands, options, and file paths are highlighted differently.

    Notes

    The chpasswd command is used to update passwords for multiple user accounts in batch mode. It's particularly useful for system administrators who need to change passwords for many users at once.

    Important security considerations:

    • Using chpasswd with plain text passwords in scripts or command lines may expose passwords in process listings or shell history.
    • It's recommended to use encrypted passwords (-e option) when possible.
    • Modern systems should use SHA256 or SHA512 encryption methods rather than the older DES or MD5.
    • The command requires root privileges to change user passwords.
    • The input format must be "username:password" with one entry per line.

    When using chpasswd in scripts, consider using process substitution or temporary files with appropriate permissions to minimize security risks.

    Related Commands

    These commands are frequently used alongside chpasswd or serve similar purposes:

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    Use Cases

    Learn By Doing

    The best way to learn Linux commands is by practicing. Try out these examples in your terminal to build muscle memory and understand how the chpasswd command works in different scenarios.

    See ExamplesTry Lab Exercises
    $ chpasswd
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