ac: Print statistics about users' connect time.
accton: Turn on accounting of processes. To turn it on type "accton /var/log/pacct".
adduser: Ex: adduser mark - Effect: Adds a user to the system named mark
chage: Used to change the time the user's password will expire.
chfn: Change the user full name field finger information
chgrp: Changes the group ownership of files.
chown: Change the owner of file(s ) to another user.
chpasswd: Update password file in batch.
chroot: Run command or interactive shell with special root directory.
chsh: Change the login shell.
edquota: Used to edit user or group quotas. This program uses the vi editor to edit the quota.user and quota.group files.
faillog: Examine faillog and set login failure limits.
finger: See what users are running on a system.
gpasswd: Administer the /etc/group file.
groupadd: Create a new group.
grpck: Verify the integrity of group files.
grpconv: Creates /etc/gshadow from the file /etc/group which converts to shadow passwords.
grpunconv: Uses the files /etc/passwd and /etc/shadow to create /etc/passwd, then deletes /etc/shadow which converts from shadow passwords.
groupdel: Delete a group.
groupmod: Modify a group.
groups: Print the groups a user is in
id: Print real and effective user id and group ids.
last: Display the last users logged on and how long.
lastb: Shows failed login attempts. This command requires the file /var/log/btmp to exist in order to work.
lastcomm: Display information about previous commands in reverse order. Works only if process accounting is on.
lastlog: Formats and prints the contents of the last login.
logname: Print user's login name.
newgrp: Lets a suer log in to a new group.
newusers: Update and create newusers in batch.
passwd: Set a user's pass word.
pwck: Verify integrity of password files.
pwconv: Convert to and from shadow passwords and groups.
quota: Display users' limits and current disk usage.
quotaoff or quotaon: Turns system quotas off/on.
quotacheck: Used to check a filesystem for usage, and update the quota.user file.
repquota: Lists a summary of quota information on filesystems.
sa: Generates a summary of information about users' processes that are stored in the /var/log/pacct file.
smbclient: Works similar to an ftp client enabling the user to transfer files to and from a windows based computer.
smbmount: Allows a shared directory on a windows machine to be mounted on the Linux machine.
smbpasswd: Program to change users passwords for samba.
su: Ex: su mark - Effect: changes the user to mark, If not root will need marks password.
sulogin: Single user login.
useradd: Create a new user or update default new user information.
userdel: Delete a user account and related files.
usermod: Modify a user account.
users: Print the user names of users currently logged in.
utmpdump: Used for debugging.
vigr or vipw: Edit the password or group files.
w: Display users logged in and what they are doing.
wall: Send a message to everybody's terminal.
who: Display the users logged in.
whoami: Print effective user id.
