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Linux User Management

June 14th, 2009

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. If the environment variable EDITOR is set to emacs, the emacs editor will be used. Type “export EDITOR=emacs” to set that variable.
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. Type “touch /var/log/btmp” to begin logging to this file.
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        Turns system quotas off.
quotaon        Turns system quotas 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.
ulimit        A bash builtin command for setting the processes a user can run.
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        Edit the password or group files.
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.

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