8.23 Lesson-3

Basic feature 21, text name "wildcard"

Meaning of special symbols

* Any character of any length

? Any single character

[: Alnum:] Large, lowercase letters and numbers

[: Alpha:] large, small letter

[: Upper:] Uppercase

[: Lower:] lowercase letters

[:d Igit:] Number

[: Space:] white space characters

[:p UNCT:] Special symbols

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Displays files that begin with a non-letter in/tmp

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Copy the files ending in/etc under. D to/tmp/1/

2. Key combination

Ctrl+l Clear Screen

CTRL + a back to command line

Ctrl+e back to command line end

CTRL + C cancels execution of commands

Ctrl+u Delete the cursor to the beginning of the content

Ctrl+k Delete the cursor to the end of the line

3. IO Redirection and piping

Standard input Keyboard 0/dev/stdin

Standard output Monitor1/dev/stdout

> Overwrite redirects

>> Chasing heavier orientation

Set-c overwrite redirect, if file exists, do not execute

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+c back to normal, can overwrite redirect to existing file

Standard Error Output Monitor 2/dev/stderr

Error redirection

2> Error Overwrite redirect

2>> Error Append redirect

Simultaneous redirection (correct + error)

1. COMMAND >/path/to/file.out 2>/path/to/file.err

2. COMMAND >/path/to/file.out 2>&1

3. COMMAND &>/path/to/file.out

Input redirect

<<

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TR command

-D Delete

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The former command: A-Z of uppercase letters to replace the lowercase a-Z

The latter command: remove a-f letters

Tee command

Used to redirect data to a file, on the other hand, you can also provide a copy of the redirected data as a stdin of subsequent commands. The simple thing is to redirect the data to a given file and screen.
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WC, cut, sort, uniq

WC command Word Count

-L count rows

-W statistical number of words

-C Statistics byte number

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From left to right, number of lines of words in bytes

Cut command

-D Specify delimiter

-F Displays the specified column

#显示 # Columns

#-#显示 # to # columns

#,#, #显示 #,#, #列

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Sort order Output

-T Specify delimiter

-K #按照指定的列排序

-n Sort by numeric size

-R Reverse Order

-F ignores case

-U sort after go heavy

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To: As a delimiter, sort by the numeric size of the third column value

Uniq command unique to redirect to row operations

-C Displays the number of repeats per line

-D displays only duplicate rows

-U displays only non-repeating rows

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Command 1, deduplication and display of repeat times

Command 2, only duplicate rows are displayed

Command 3, show only rows that are not duplicates

8.23 Lesson-3