The Three Musketeers of Linux Foundation

One, grep: Text Search Tool

-C output only matches the number of rows

-I is case insensitive

-V filters out rows containing the specified string

-S does not display error messages for nonexistent or no matching text

-W displays only the entire word that matches, not part of the string

-N Displays matching lines and line numbers

-l list only matching filenames

-l list file names that do not match

Cases:

grep-c root/etc/passwd if the containing root string has two lines in the file, it is displayed as 2

grep-i root/etc/passwd the line that displays the root string, including its case

grep-v root/etc/passwd Show rows with root string except

grep ' test ' d* shows all lines that contain the test string in a file that begins with D

grep ' ^$ '/etc/passwd show Blank lines in the passwd file

grep ' test ' AA bb cc displays the line that matches test in the aa,bb,cc file

The main parameters of the regular expression:

\ ignore the original meaning of special characters in regular expressions

[] A single character, such as [a] that [a] meets the requirements

[-] range, such as [A-z], i.e. a,b,c to Z all meet the requirements

grep ' [a-z]\{5\} ' AA displays all lines containing a string of at least 5 consecutive lowercase characters per string, A-Z can

grep ' w\ (es\) t.*\1 ' AA if West is matched, then es is stored in memory, labeled 1, and then searched for any character (. *) followed by another ES (\1), which is found to display the row. Example: west.es west.esdd.es west.aa.es

grep test/mnt/* directory search for files with string test

grep-l test/mnt/* lists only matching file names

grep-l test/mnt/* list file names that do not match

[[: Alpha:]] single letter

[[: Lower:]] single lowercase letter

[[: Upper:]] single capital Letter

[[: Alnum:]] single letter or number

[[:p UNCT:]] single symbol with no numbers, letters, and spaces

[[:d igit:]] number

[[: Space:]] space

Example: grep ' 5[[:upper:]][[:upper:] ' AA displays lines beginning with 5 with two uppercase letters

ii. sed: Text Processing tools

-U Show modified text content, but not really change

-I directly modifies the file without displaying the content

Sed ' 1d ' file delete first line

Sed ' 2, $d ' file delete the second line to the last row

Sed ' 1a play lol ' file after the first line adds the string "Play LOL"

Sed ' 5i go die ' file added "Go die" before line 5th

SED ' 1c hi ' file first line instead of hi

Sed-n 2, ' $ ' p file shows the second line to the last row

Sed ' s/^.*asd.*$/lizekang/g ' file matches the ASD character and modifies the integer behavior Lizekang

Sed ' 14c [file] ' file modified 14 line integer behavior [file]

Sed-n '/^\//p ' file displays lines with/starting (if no-n option is present, all content in file and/or lines starting with two parts are displayed, N-mode filters out other rows, only displays/starts rows)

Sed '/^$/d ' fiel delete blank lines in a file

Sed '/^#/d ' file deletes the # number at the beginning of the document

Sed ' s/^[[:spqce:]]*//g ' fiel delete spaces at the beginning of a file

Third, awk: Text analysis tools

-F (split word): Do not add this parameter by default separated by a space.

' {print $} ': Required field, output the specific paragraph, $NF represents the last element.

awk ' {print nr,$0} ' is preceded by a line number in front of each line.

awk ' {if (nr<=3+1 && nr>=2) print $} ' outputs the second line to line fourth.

Netstat-an|awk '/^tcp/{++state[$NF]} END {for (I in State) print I, "\ T", state[i]} '

/^tcp/filter out the records of the beginning of TCP, shielding Udp,socket and other unrelated records.

State[] equivalent to defining an array called state

NF indicates the number of fields recorded

State[$NF] Represents the value of an array element, such as the number of connections on state[time_wait]

++state[$NF] Number of connections above plus 1

Here are some of awk's exercises:

1. Print the entire test.txt with awk (the following operations are implemented with the awk tool for Test.txt);

awk ' {print $} ' test.txt

2. Find all rows that contain ' bash ';

awk '/bash/' test.txt

3. Use ': ' as a delimiter to find the line with the third paragraph equal to 0;

awk-f ': ' $3== ' 0 "' Test.txt

4. Use ': ' as a delimiter to find the first line of ' root ' and replace that segment ' root ' with ' Toor ' (which can be used together with SED);

awk-f ': ' $1== ' root ' test.txt | sed ' s/root/root/g '

5. Use ': ' as a separator to print the last paragraph;

awk-f ': ' {print $NF} ' Text.txt

6. Print all rows with a number of rows greater than 20;

awk-f ': ' nr>20 ' Test.txt

7. Use ': ' As a delimiter to print all third paragraphs less than the fourth paragraph;

awk-f ': ' $3<$4 ' Test.txt

8. Use ': ' As a separator, print the first paragraph and the last paragraph, and the middle with ' @ ' connection (for example, the first line should be the form of "[Email Protected]/bin/bash";

awk-f ': ' {print $ ' @ ' $NF} ' test.txt

9. Use ': ' As a delimiter to add and sum the fourth paragraph of the entire document;

awk-f ': ' {(sum+=$4)}; END {print sum} ' test.txt

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The Three Musketeers of Linux Foundation