user
useradd user1 // Create user user1
userdel user1 // delete user user1
userdel -r user1 // delete the user's home directory and delete content
password user1 123 // set password user1
echo 123 | passwd --stdin user1 // set password user1
useradd -s / sbin / nologin user1 // Create user user1, SHELL part nologin (non-logged-in user)
useradd -G user1, user2 user3 // user3 new user, and the user is added user1, user2 additional set
// display user1 user1 user id id number, group number
cat / etc / passwd | grep user1 // user1 to view
/ Etc / passwd // This file records the user ID and
/ Etc / skel / // skel directory as a template directory, if new files and folders in the skel directory, there will be the new user home directory created
/ Var / spool / cron after // delete a user, the contents of this folder there is residual information needs to be removed
/ Var / spool / mail after // delete a user, the contents of this folder there is residual information needs to be removed
usermod -e 2000-01-01 user1 // modify user1 users, their passwords expire in 30 days
chage -l user1 // View user user1 effective date
group
groupadd -g 30000 pgroup // create additional groups, group name pgroup, group ID 30000
groupadd badgroup // create a group, the group name badgroup
groupdel pgroup // delete pgroup group
cat / etc / group | grep badgroup // view the information specified group
usermod -G pgroup user1 // user1 user to add additional groups in pgroup
cat / etc / passwd | grep user1 // see if the added successfully