Shell Basics (2)

Special symbols in the 1.linux shell
(1) "*" represents 0 or more arbitrary symbols
(2) "? "represents only one arbitrary symbol
(3) "#" comment Description, "#" after the content will be ignored
(4) "\" caret character, "\" After the special symbol will be restored normal symbol
(5) "|" Pipe character, with the preceding input as the following input

2. Command cut: intercepts a field
Usage: cut/etc/passwd |cut-d ': '-F 1 |head
Format: cut-d ' delimited character ' [-CF] n N represents a number
-D: followed by the assigned character
-C: followed by the first few letters
-F: The next section is followed by the number of blocks


3. Command sort: Sort
Usage: sort-t:-kn1-n
Format: Sort [-t delimiter] [-KN1,N2] [-nru]



4. Command WC: Statistics
-L (number of rows)-m (characters)-W (number of words)

5. Command uniq: Delete duplicate rows
Usage: uniq-c
6. Command Tee:tee followed by the file name, the files are written to the following file display
Usage: | Tee file name
7. Command tr: Replacement character
-D: Delete a character followed by the character you want to delete
-S: Remove duplicate characters

8. Command split: Cutting documents
-B: Cutting documents according to size
-L: Number of rows cutting document

9. Special symbol $: Last variable in "!$" command

10. Special symbols ";" : Multiple commands can be run in a row

11. Special symbol: "~" User home Directory

12. Special symbol: "&" to run the command in the background

13. REDIRECT symbol: ">" ">>" "2>" "2>>"
">" ">>" represents "Replace" "append" respectively
14. Special symbols: []

15. Special symbols: "&&" "| |"
"&&" when used, only after the successful execution of the previous, the subsequent execution
"| |" When used, no matter the previous execution is unsuccessful, the following execution

20180604

Shell Basics (2)