2.3 Other system user accounts

Other system users As you begin to explore the filesystem you will notice that some files are owned by users that you did not manually create. These are important users - although no one actually logs in as them. Vendors use different mechanisms to prevent users from logging in using these accounts. Some will place an asterisk in the account's password field, some will use the letters NP, and others will use a similar technique. The system users we will cover in this section are bin, daemon, and nobody. The bin user is typically the owner of directories where system commands reside - /bin and /usr/bin are two examples. Most executable files on the system are also owned by bin. The daemon user is assigned ownership of key system-level files to eliminate security risks that would be created if the root user owned the same files. This user should NOT be confused with daemon processes. The nobody user owns files that do not require any special permissions. A few other system users that you will find on your lab system are uucp, adm, lp, sys, listen, and nobody4.

Hands-on Exercise - View the contents of /etc/passwd and /etc/shadow

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