Manage Users and Groups Flashcards
1
Q
create a new user
A
#useradd user1 by default a home directory is created under /home #useradd -c "Full name" user1 # useradd -s /bin/tcsh user2 change user's shell # useradd -c "full name" -d /home/location user change user's home directory location #useradd -G wheel bob add bob the wheel's group as the account is created #useradd -u 504 -g 505 bob add user bob with uid 504 and GID 505, the gid must already exist
2
Q
delete a user
A
# userdel user1 by default userdel doesn't remove the home directory, nor delete mailbox #userdel -r user1 removes user's home directory & mailbox # userdel -f bob also remove home directory & mail spool even if the user is logged on
3
Q
modify user’s account using usermod
A
usermod uses some of the same commands as useradd #usermod -c "full name" user2 #usermod -s /bin/bash bob change bob's shell to bash #usermod -a -G sales bob modify bob to be in the sales group #usermod -l usr user change the name of a user account(from usr-user)
4
Q
How to add/remove/modify users from the GUI
A
You might need to install it first # yum -y install system-config-users # system-config-users or from the GUI System -> Administration -> users & groups
5
Q
change user’s password
A
#useradd -p test123 newUser create user with a password #passwd user change user's password account is disabled if no password is provided
6
Q
locking and unlocking a local user’s account
A
#passwd -l user to lock a user's account #passwd -u user to unlock a user's account #usermod -L username locks an account #usermod -U username unlocks an account
7
Q
Setting user’s password expiration
A
By default there is no expiration set for a user's password, but you can set that using the chage command #chage -M 90 user1 set password expiration to 90 days(user must change in 90 days) #change -E 2012-5-25 user set expiration for a user on a specific day You can also use the passwd command to set expiration for a user's password #passwd -x 30 user set password to expire in 30 days
8
Q
Other chage commands
A
#chage -l user check a user's policy
Also this command will let you see the status of an account
#passwd -S user
#chage -w 2 user set warning to 2 days prior to password expiration
#change -m 10 user allow a user to change their password every 10 days and no more.
#chage -d 0 user apply immediate expiration
9
Q
chage command line options and meanings
A
- m -> specifies the minimum number of days between which the user must change password. if the value is 0, the password does not expire
- M -> specifies the maximum number of days for which the password is valid
- d -> specifies the number of days since Jan 1 1970 the password was changed
- I -> specifies the number of inactive days after the password expiration before locking the account. If set to 0, the account is not locked after the password expires
- E -> specifies the date on which the account is locked, in the format YYYY-MM-DD. Instead of the date, the number of says since Jan 1 1970 can also be used
- W -> specifies the number of days before the password expiration date to warn the user
10
Q
To create a group
A
#groupadd research for new group memebership to take effect after adding a user to a group, a user must log out, then log back in or run #newgrp groupname
11
Q
to check which groups user belongs to
A
#groups as the user #groups user as root
12
Q
to modify group’s attribute
A
groupmod -n group1 group2
13
Q
Change group id
A
groupmod -g 1000 group2
14
Q
granting non-root user right to add users to a group
A
#gpasswd -A user groups2 user acting as group administrator now as the group administrator #gpaswd -a user5 group2
15
Q
to delete a group
A
#groupdel group2 you can also use the user & group gui tool to add/delete groups
