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Format of `/etc/passwd`

Updated Mar 21, 2021 ·

The /etc/passwd file stores user account information. Each line in this file represents a single user and contains seven fields separated by colons (:). This is a sample /etc/passwd file:

root:x:0:0:root:/root:/bin/bash
daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
bin:x:2:2:bin:/bin:/usr/sbin/nologin
sys:x:3:3:sys:/dev:/usr/sbin/nologin
john:x:1001:1001:John Doe:/home/john:/bin/bash
jane:x:1002:1002:Jane Smith:/home/jane:/bin/zsh

The format:

username:password:UID:GID:full_name:home_directory:shell

Field Descriptions​

  1. username:

    • This is the name the user types when logging in.
    • It must be unique and typically contains 1-32 characters.

  2. password:

    • Historically, this field contained the hashed password, but for security reasons, modern systems store the hashed passwords in the /etc/shadow file, and an "x" is placed in this field to indicate that.

  3. UID (User ID):

    • This is a unique identifier for the user.
    • The root user typically has a UID of 0.
    • Regular users usually start with a UID of 1000 or 500, depending on the system.

  4. GID (Group ID):

    • This is the primary group ID associated with the user.
    • The group details can be found in the /etc/group file.

  5. full_name:

    • This field can contain the user's full name or other descriptive information.
    • It can include multiple comma-separated values for additional info, but typically it's just the full name.

  6. home_directory:

    • This is the path to the user's home directory.
    • It's where the user is placed upon logging in and where user-specific files and directories are stored.

  7. shell:

    • This is the path to the user's default shell.
    • Common shells include /bin/bash, /bin/sh, /bin/zsh, etc.
    • If set to "/sbin/nologin", user will not be able to loginn through SSH. If user tries to login, connection is closed.
    • If user is currently logged-in when shell is changed to nologin his connection will continue but if he logs out, he wont be log back again.