Awk command Basics

Basic commands

Awk '{action}' input file	Unconditionally execute action
Awk '/pattern/{action}' input file	Execute action when pattern matches
Awk '(condition) {action}' input file	Execute action when condition is set

Awk '/Li Si/{print $0}' TMP // output a line record containing the 'Li si' keyword 2 Li si70awk '/^ 2/{print $0}' tmp // output the record of a line starting with 2 2 Li Si 70

About fields:
The awk command splits each line into multiple fields. Each field is separated by a specified or default delimiter. The default Delimiter is tab and space. You can use $1, $2, to access the corresponding fields. The fields start from 1, and $0 indicates the entire row.

Built-in Variables

$0	Current row record
$1 ~ $ N	The Nth field of the current record, which is separated by FS
FS	The input field delimiter. The default Delimiter is space.
RS	The input record delimiter. The default value is a line break.
OFS	The delimiter of the output field is also a space by default.
ORS	Output record separator. The default value is line break.
NF	Number of fields in the current record
FNR	Number of lines of processed files, limited to the current file
NR	Number of lines of processed files, multiple files are accumulated
Argc	Number of command line parameters
Argv	Command Line Parameter Array
Filename	Name of the current input file
Ignorecase	Specifies whether to ignore the case sensitivity when matching.
Environ	UNIX environment variables
Errno	UNIX system error message
Convfmt	Conversion format of numbers to strings
Ofmt	Set the output format of a number
Rstart	First String matched by the matched Function
Rlength	String Length matched by the matched Function
Fieldwidths	Blank separator string of the input field width
Argind	Argv identifier of the currently processed file

 
 

The tmp file contains: ID, name, scoreawk '{print filename, argc, argv [0], argv [1]} 'tmptmp 2 awk tmpawk-F ', ''{print NF, FS, FNR, FS, NR, RS} 'TMP tmpps:-F, specifying a comma as the field separator 3, 1, 13, 1, 2 awk '{print environ ["path"]} 'tmp/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin: /sbin:/bin:/usr/games:/usr/local/gamesawk '{convfmt = "% F"; printf "% s \ n ", 0.11} 'tmp0.1120.awk' {ofmt = "% 0.2f"; print 1/3} 'tmp0.33awk' {match ("tmp123tmp",/123/); print rstart, rlength} 'tmp4 3

Operator

=, + =,-=, * =,/=, % =, ^ =	Assignment Statement
|	Logic or
&&	Logic and
~ ~!	Match Regular Expressions and do not match Regular Expressions
<, <=,>, >= ,! =, =	Relational operators
+ ,-,*,/,	Addition, subtraction, multiplication, division
**, ^	Power
!	Non-logical
++ ,--	Auto-increment and auto-Increment
$	Field Reference
Space	String Connector
? :	C-condition expression
In	Whether a key value exists in the array

In? : Awk 'in in {A [1]; A [2]; print 1 in? "Yes": "no"} 'regular expression match: awk-F ","' {if ($3 ~ /70/) printf "% S score % d \ n", $2, $3} 'tmp Li siscore 70 power: awk-F ", "'{TMP = $3 ^ 2; If (TMP >= 6400) printf" % S score % d \ n ", $2, $3} 'tmp King Five score 80 space: awk' begin {print "1" 2 "} '12awk' begin {print" 1 "," 2 "} '1 2

Array

The awk array is a set of key-value pairs. The subscript of the array can be numbers and letters. The values and keywords are stored in an internal table that uses hash for key/value.

awk 'BEGIN{a[z]="sky123";print a[z];}'sky123

Redirection

awk 'BEGIN{print "1" >> "1.txt"}' | cat 1.txt1ls |awk 'FS==" "{print 1}'1

Process control statement

When a break statement is used for a while or for statement, the exit program loop occurs. When a continue statement is used for a while or for statement, the program moves cyclically to the next iteration. Next can read the next input line and return to the top of the script. This avoids other operations on the current input row. Exit causes the main input to exit cyclically and transfers the control to the end (if the end module exists ). If the end module is not defined or the exit statement is applied to the end, the execution of the script is terminated.

Begin and end

Awk 'in in {action}/pattern/{action} end {action} 'input file

Awk 'in in {print "begin"}/Zhang San/{print $0} end {print "end"} 'tmpinin1, Zhang San, 60end

If:

if (condition1) {    action1} else if (condition2) {    action2} else {    action3}

awk 'BEGIN{if(FNR==1) print 1;else print 2;}'2

While

while(condition){    action3}

awk 'BEGIN{a=1;while(a<5){a++;if(a>3) break;}print a;}'4

For

For (variable in array) {action3} For (variable; condition; expression) {action3}

awk 'BEGIN{a[1]=100;a[2]=200;a[3]=300;for(i in a){if(i==2) continue;print a[i];}}'100300awk 'BEGIN{a[1]=100;a[2]=200;a[3]=300;for(i=1;i<=3;i++){if(i==3) exit;print a[i];}}'100200

Do

do{action3}while(condition)

awk 'BEGIN{a=1;do{a++;}while(a<5)print a;}'5

Awk command Basics