User-Related

Command Description
id Shows the active user and group information. With -G switch you can view the IDs of groups
last Shows a list of last logins on the system. Using -a switch you can add the hostname to the last column of the output
who Shows who is logged on the system
groupadd admin Adds the group “admin”
useradd -c “Sam Tomshi” -g admin -m sam Creates user “sam” and adds to group “admin”
userdel sam Deletes user sam
adduser sam Adds user “sam”
usermod Modifies user information
passwd user1 Changes the password of user1