Mastering Embedded Linux Programming - Second Edition

Configuring user accounts

As I have hinted already, it is not good practice to run all programs as root, since if one is compromised by an outside attack, then the whole system is at risk. It is preferable to create unprivileged user accounts and use them where full root is not necessary.

User names are configured in /etc/passwd. There is one line per user, with seven fields of information separated by colons, which are in order:

• The login name
• A hash code used to verify the password, or more usually an x to indicate that the password is stored in /etc/shadow
• The user ID
• The group ID
• A comment field, often left blank
• The user's home directory
• (Optional) the shell this user will use

Here is a simple example in which we have user root with ...