User Management:
1, useradd to create the user
- C specified user description
- D designated home directory
- G specify the group
- G specify additional group can have a plurality of sets of additional special program to specify shell -s / sbin / nologin -> does not allow a user login - U UID specified -m not create home directory
2, userdel Delete user
-r delete a directory with family
3, usermod modify user
- C Modify User Description
- D modifying (create) home directory
- G modify the primary set
- G Additional modifications group - m Mobile home directory modifications -o allows the same UID and - used with modified UID u -u
4、passwd
- L lock password
- U unlock
- d delete password
echo "password" | passwd -stdin "username"
5, group management
gropadd Add Group
- G Modify Group ID
- O reuse allowed
groupdel delete group
groupmod modifying group
- G <Group ID> Set group ID to be used is - O group identifier code reuse - n-modifying group name specified -p set password
6, popular file
/ etc / the passwd
the uname : X: UID: GID: Description: home directory: shell program
/ etc / Shadow
the uname : UID: Password: various time
/ etc / Group Group File Group: Group Password: Group ID: Additional Group / etc / gshadow group password file uname : password: user group administrator name: support account name / etc / skel
by default, files in this directory will be copied to each ordinary user's home directory, generally used to make caveat
7, user rights
R & lt . 4 Read
W 2 Write
X . 1 performs
the chmod [A | G | O | U] [+ | - ] Add a file or delete permissions
chown : User file modification belonging group
chown User: file modification master belongs
chown User: User file modification belongs main group and belongs
8, acl license management
setfacl add permissions
setfacl - MU: user: rw rw rights users to add a file called
setfacl - xu: Username Cancel file permissions
getfacl
view acl permission to add
9, special privileges
Temporary permission to borrow, for example: there are two users belong to AB group AA and BB groups; creates a a.txt A, B default access a.txt continue to use other authority; when privileges A B wants to borrow visit a. txt; SUID must be set to 1; also can borrow the SGID permission to access files;
SUID
chmod + U S special privileges granted to SUID file name, and if the owner has permission to display x s, x is not displayed S.
SGID
chmod G + S special permission granted SGID file name, if there is a set of permissions displayed as x s, x is not displayed S.
Sticky sticky bit, authorize a directory, all users can delete their own files in the directory, you can not delete other people's files.
chmod o + t directory sticky bit permissions granted to the file, if there are other people permission to appear as x t, x does not display T.
10, su Authorization
/ Etc / sudoers in this file inside to add permissions to