Grep, cut, seq, sort, wc, uniq in Linux advanced command

Grep

Grep command: matches the keyword, that is, displays the entire line of the keyword in the file.

Show all lines in the / etc/passwd file that contain the root keyword: grep root / etc/passwd

Displays all lines in the / etc/passwd file that contain the root keyword and shows which line the keyword is in the text:

Grep-n root / etc/passwd

-n display line number-v inverted

-I is case-insensitive-c the number of lines with keywords

-Q execute silently, that is, the matching content is not displayed on the screen

-A shows a few lines after the keyword

Grep-A 2u1 / etc/passwd shows the line where U1 is located, and the next two lines

-B to show the lines before the keyword

Grep-B 2u1 / etc/passwd shows the line of U1, and the previous two lines

-- color displays keywords with color

Grep root / etc/passwd-- color

Cut

Cut command: extract the fields (columns) and character contents specified in the contents of the file. The default delimiter for a word is a space.

-b: according to byte cutting, each Chinese character occupies 3 bytes in utf-8 coding

-c: cut by the character-d: specify the delimiter

-f: specify which field is separated by the delimiter

Example: cut-d:-f 1J 6 / etc/passwd

Displays the contents of columns 1 and 6 split by: in the file

Cut-d:-f 1Magol 3-5 / etc/passwd displays 5 columns of content in the file with: segmented 1pr 3pr 4 Jol.

Cut-d:-f-3 / etc/passwd

Display the first three columns in the file

Cut-d:-f 3-/ etc/passwd

Displays the contents of the third to last columns of the file

Cut-c 1-3 / etc/passwd take the first three characters of each line

Echo 'Welcome' | cut-b 1-6 take the first six bytes of 'Welcome'

Seq

Seq: print some numbers in order

Basic usage: seq [options]... Mantissa

Seq [options]... First and Mantissa

Seq [options]... First increment Mantissa

Example: seq 1 2 10 outputs odd numbers between 1 and 10

Seq 2 2 10 outputs even numbers between 1 and 10

Seq 10-2 1 outputs even numbers between 10 and 1

The same effect can be achieved with echo

Echo {first count. Mantissa. Increment}

Echo {1... 10} outputs 1 to 10 integers

Echo {1... 10... 2} outputs odd numbers from 1 to 10.

Echo {2... 10... 2} outputs an even number between 1 and 10.

Echo {10... 1... Mel 2} outputs even numbers between 10 and 1.

Sort

Sort sort (ascending, descending) default ascending order

-n: (numeric-sort numeric sort) default single character comparison based on numeric comparison

-r:reverse (reverse) output results in reverse order

-t: specify the delimiter (separator separator)

-k: sort build (key, sorted column field)

-u: remove duplicate lines (uniq unique)

Example: create a.txt with cat command

Sort-n-r-t:-k 3 a.txt

Output in reverse order by: partitioned third column

Sort-u a.txt

Remove duplicate lines from the a.txt file

Wc

Wc counts lines, words and bytes

-l: count the number of rows

-c: count the number of bytes

-w: count the number of words

-m: count the number of characters

Example: wc-l / etc/passwd statistics on the number of lines in a file

Uniq

Uniq merges consecutive duplicate rows

-u: only lines that do not have consecutive repeats are displayed

-c: count the number of consecutive repeated rows

-d: displays only one row that repeats continuously

-I: ignore case

Example: cat > a.txt