Linux administrator course study notes.

Commands:

su == SwitchUser

ls == list

ls -la == list -long format; all (includes .hidden files)

chmod == changeMode (Read, Write, Execute; Owner, Group, User)

Read = 4, Write = 2, Execute = 1

useradd account == adds a user with the username supplied.

passwd account == changes the password for the specified account.

Folders/Files:

/etc/passwd contains a line for each account

/etc/shadow contains additional account information

/etc/groups unique group names

/etc/gshadow more group information

useradd creates a folder for each username in the /home/ folder. It then copies the contents of /etc/skel to the user’s home folder. /etc/skel contains files such as .bash_profile.

Shutting down and rebooting:

• poweroff: Shuts down the system
• halt: Shuts down the system
• reboot: Reboots the system

shutdown -h, shutdown -r (shutdown –halt, shutdown –reboot). Shutdown requires additional commands such as “now” or hh:mm or +minutes. For example:

shutdown -r now

Logging out:

exit logs you out of ssh or su

logout closes the whole session including ssh and su

ctrl+d does the same thing as exit