1) grep text filter
Syntax: grep [options] mode or keyword file list
--clolor color display matches to the keyword
-I ignores case
-V Take reverse
^ Start with a keyword
$ ends with a keyword
^$ Empty Line
The number of rows to which the-C statistic matches
-L is used with-R to display only the name of the file containing the keyword
-R Recursive display
-Q Silent Output (used when writing scripts)
-N Displays the line number of the matching row
2) Cut intercept
Syntax: cut-f specifies the column-d ' delimiter ' (-d specifies the field delimiter,-f specifies the range to be output, and more than one comma-delimited,-c-specified column character)
3) sort order (-t Specify field delimiter,-K to specify the number of fields,-N to sort by numeric,-R to reverse, and-u to sort after duplicate rows to print once)
4) Uniq ' only (-C displays the number of repeated rows,-I ignores case) first sort and then go to heavy
5) TR main role text conversion or deletion, paste text merge, middle using tab-separated,-D to specify the delimiter between the rows of the merged file
6) Users and Groups
1. User: Identity used for different functions of the operating system
Users in 2.Linux: Root uid=0, System user, normal user
3. Create User: Useradd username
Delete User: Userdel username
Set User password: passwd username
Modify user information: Usermod-[u, G, G] username
View Current User: ID
View specified User: ID LP
4. Create Group: Groupadd groupname
Delete Group: Groupdel groupname
Modify group information: Groupmod groupname
Delete Group member: gpasswd-d username Group
5.usersdd
-U Specify user uid
-G Specify user gid
-g Specifies the subordinate group
-C Develop a description
-D Specify home directory
-M do not set up home directory
-S Specify shell
-e Specify user expiration time (date)
-F Specify user Expiration Time (days)
6.usermod
-L Lock User
-U Unlock User
-L Renaming
-A Add user to group
7.passwd
-L Lock User
-U Unlock User
-N Password minimum usage period (days)
-X Password maximum lifespan (days)
-W Reminder days before expiration (days)
7) Basic Permissions
1. Documents
R: Readable
W: Writable
X: Executable
2. Catalogue
R: Can execute LS on this directory
W: You can create files in this directory
X: You can switch with CD
3.chown Change file owner (root use)
-R Modify the owner of the directory and internal files
4.chmod Modifying file permissions
Linux basic Commands (ii)
