Understanding passwd file

Created: 2022-07-09
Tags: #fleeting

Can be found at /etc/passwd
passwd is a plain text file

Contains list of

• system accoutnss
• each account has info about user ID, group ID, home directory, shell etc..

Quick Tips

• Name of the user is usually found at the end of the file

All fields are separated by colon symbol. All have 7 fields

1. Username
   Username, that's it. What more can you ask for?

2. Passoword
   -> x character indicates encypted password is stored at /etc/shadow.

passwd
You need to use passwd command to compute hash of a password typed at CLI
Store/update the hash of the password in etc/shadow file.

3. User ID (UID)
   Each user must be assigned with an ID
   0 reversed for root
   1-99 for other predefined accounts
   100-999 for administrative and system accounts/groups

4. Group ID (GID)
   Primary group ID (stored in /etc/group)

5. User ID Info (GECOS)
   Comment field. Allows you to add extra info.

6. Home Directory
   Absolute path to directory when user will be logged in

7. Command/Shell
   Absolute path of command/shell (bin/bash)
   Please note that it does not have to be a shell
   sysadmin can use the nologin shell, sbin/nologin