Linux wildcard, linux wildcard

Linux wildcard, linux wildcard

Learning wildcards is a bit of a basic feeling for regular expressions ...... I have learned Regular Expressions in python before, so this blog is still very fast.

Special symbols

| # Pipeline character, or (Regular Expression)> # output redirection> # output append redirection <# input redirection <# append input redirection ~ # The current user's home directory ''$ () # reference the result $ # After the command is executed... End (Regular Expression) ^ #... Start with (Regular Expression) * # match all characters. What are the wildcards? # Any character, wildcard ## Note & # Switch the program or script to the background for execution & # And set [] # to indicate a range (regular expressions, wildcard characters) {}# generate a sequence (wildcard ). # Hard link of the current directory .. # Hard link of the parent directory

Wildcard

It is a built-in function of shell.
Wildcard characters, which are common and should be well understood when DOS is used.
A wildcard character string "?" That contains these characters. "*", "[]", {}

Wildcard characters ==> match file names

 

Symbol	Function
*	Match any string/text, including null strings; * represents any character (0 or multiple) ls file *
?	Match any character (when not in parentheses )? Represents any 1 character ls file 0
[Abcd]	Match any character in abcd
[A-z]	The range is a to z, indicating that the range means [] matching any character in brackets ls file 0
{..}	Generation sequence. separated by commas (,) and no space is allowed.
Supplement
[! Abcd]	Or [^ abcd] indicates no, indicating that it does not match any character in the brackets

Wildcard details

? Any one character

[Abcd] indicates matching any character in the brackets.

• {} Generation Sequence

• [] Used to find a file (matching the file name)

Back up {}

[^ Abcd]! ^ Indicates non, reverse

[] And {}

• [] Can only be used to find files
• {} Is used to find a file or create a file to generate a sequence.

 

Special symbols

Command 1 | command 2 ### pipeline symbol, which is a common text and string passed by the previous command. | Xargs ### pipeline symbol. Use the xargs Pipeline character command to convert a string to a file name.

Directory structure

. # Current Directory (or "any character" regular) .. # The upper-level directory of the current directory

Redirection symbol

> # Output redirection: the original content is cleared, and content is appended to the file >># append output redirection, append to the last line of the file <# input redirection tr xargs <# cat is used to append multiple lines of text to the file

 

Unclassified special symbol # comment

Linux will ignore him and explain it to the O & M personnel.

$ Reference a variable to a variable value or a command prompt from a common user

1. shell
$ Variable: Get the content in the Variable

2. awk
$ Retrieve column $ number

3. Command Prompt for common users

'(Below esc) refers to the result of referencing the command in reverse quotes, which is equivalent to $ ()

; Separate multiple commands, no logical relationship, just one step

1. shell

2. sed

[root@chengliang ~]$ seq 100 | sed -n '20p;50p;100p'2050100

Cd-; su-

• Cd-### return the last working directory and the last position
• Su-### switch users,Reload Environment Variables

 

~ Home Directory of the current user, home

[Root @ chengliang ~] $ Cd ~ Returns the Home Directory of the current user.

 

\ Escape characters or alias Blocking

. # (Any character in the regular expression) \. # it only represents the symbol of a vertex.

 

! Indicates non-

Indicates force
Vi/vim
Vi force exit (: q !)

 

& Represents and

Note:& The symbol indicates that the subsequent command is executed only when the command of the current edge is successfully executed.

Single quotes, double quotes, no difference in quotation marks

• Single quotes: What you see is what you get.

• Double quotation marks: special characters are parsed. special symbols have special meanings.

• No quotation marks: Special. Wildcards are supported.

 

Reference blog: http://www.cnblogs.com/chensiqiqi/p/6280351.html