Awk - Revision history

Hdridder: /* String manipulation */

2023-11-13T14:50:03Z

String manipulation

← Older revision		Revision as of 14:50, 13 November 2023
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	==~~String manipulation~~==		==Strings==

			;length(<sting>)
			:The length of <string>

	;substr(<string>,<start>,<num>)		;substr(<string>,<start>,<num>)

Hdridder at 10:04, 14 September 2023

2023-09-14T10:04:12Z

← Older revision		Revision as of 10:04, 14 September 2023
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	;awk -F"," -v VAR=<value> '{codeblock}'		;awk -F"," -v VAR=<value> '{codeblock}'
	:In awk: Use "," as field-separator and set VAR to <value>. With -v you can pass variables from the shell to the awk program.		:In awk: Use "," as field-separator and set VAR to <value>. With -v you can pass variables from the shell to the awk program.

			;awk -f <awkfile> <file>
			:Parse <file> with the code in <awkfile>. If - is provided as <file> the text to parse can be given after pressing return, close the input with CTRL-D

	;awk '{ for(i = 1; i <= NF; i++) { print i,$i; } }'		;awk '{ for(i = 1; i <= NF; i++) { print i,$i; } }'

Hdridder: /* Standard variables */

2022-09-20T09:22:24Z

Standard variables

← Older revision		Revision as of 09:22, 20 September 2022
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	*NF Number of fields on the line		*NF Number of fields on the line
	*FS The field separator (default is whitespace)		*FS The field separator (default is whitespace)
			*OFS The output field separator. Set like '{BEGIN OFS=","} {<other code>}'
	*$0 The entire line		*$0 The entire line
	*$1 First field in line		*$1 First field in line
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	;awk '{if (ARGIND==2) {codeblock}'		;awk '{if (ARGIND==2) {codeblock}'
	:Execute codeblock if the current line is in the second file passed to awk		:Execute codeblock if the current line is in the second file passed to awk


	==Arrays==		==Arrays==

Hdridder at 12:09, 1 April 2022

2022-04-01T12:09:28Z

← Older revision		Revision as of 12:09, 1 April 2022
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	[[Category:Linux/Unix]]		[[Category:Linux/Unix]]
	==Basics==		==Basics==

	~~;awk -F"," -v VAR=<value> '{codeblock}'~~
	~~:In awk: Use "," as field-separator and set VAR to <value>. With -v you can pass variables from the shell to the awk program.~~

	~~;awk '{ for(i = 1; i <= NF; i++) { print i,$i; } }'~~
	~~:Iterate over all fields~~

	===Standard variables===		===Standard variables===
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	*$1 First field in line		*$1 First field in line
	*NR The number of the current line		*NR The number of the current line
	*ARGV The arguments (files) passed to awk		*ARGV The arguments (files) passed to awk (ARGV[2] has the name of the 2nd file on the commandline)
	*ARGIND The argument number currently processed		*ARGIND The argument number currently processed


			;awk -F"," -v VAR=<value> '{codeblock}'
			:In awk: Use "," as field-separator and set VAR to <value>. With -v you can pass variables from the shell to the awk program.

			;awk '{ for(i = 1; i <= NF; i++) { print i,$i; } }'
			:Iterate over all fields

	;<code>a=length(field)</code>		;<code>a=length(field)</code>
	:Get the length of a field.		:Get the length of a field.

			;awk '{if (ARGIND==2) {codeblock}'
			:Execute codeblock if the current line is in the second file passed to awk


	==Arrays==		==Arrays==

Hdridder: /* Standard variables */

2022-04-01T12:04:01Z

Standard variables

← Older revision		Revision as of 12:04, 1 April 2022
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	*$1 First field in line		*$1 First field in line
	*NR The number of the current line		*NR The number of the current line
			*ARGV The arguments (files) passed to awk
			*ARGIND The argument number currently processed

	;<code>a=length(field)</code>		;<code>a=length(field)</code>

Hdridder at 09:18, 17 November 2021

2021-11-17T09:18:55Z

← Older revision		Revision as of 09:18, 17 November 2021
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	;return <value>		;return <value>
	:End of function and give it a return value		:End of function and give it a return value

			==Date/time==
			today=`gawk 'END{print strftime("%Y%m%d",systime())}' < /dev/null`
			yesterday=`gawk 'END{print strftime("%Y%m%d",systime()-246060)}' < /dev/null`

	==Magic==		==Magic==
	;gawk '{if (NR%3 == 0) {print p$0;p=""}else{p=p$0}}'		;gawk '{if (NR%3 == 0) {print p$0;p=""}else{p=p$0}}'
	:Combine lines per 3 (Basic code found on stackoverflow [https://stackoverflow.com/questions/3194534/joining-two-consecutive-lines-using-awk-or-sed])		:Combine lines per 3 (Basic code found on stackoverflow [https://stackoverflow.com/questions/3194534/joining-two-consecutive-lines-using-awk-or-sed])

Hdridder: /* Standard variables */

2020-10-08T10:22:40Z

Standard variables

← Older revision		Revision as of 10:22, 8 October 2020
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	*$0 The entire line		*$0 The entire line
	*$1 First field in line		*$1 First field in line
			*NR The number of the current line

	;<code>a=length(field)</code>		;<code>a=length(field)</code>

Hdridder: /* Control statements */

2020-07-27T12:30:37Z

Control statements

← Older revision		Revision as of 12:30, 27 July 2020
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	:and		:and

	;If ( VAR == <value> ) { ~~<stat>~~ } else { ~~<stat>~~ }		;If ( VAR == <value> ) { codeblock } else { codeblock }
	:The if, then, else construction		:The if, then, else construction
	;if (n)		;if (n)
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	;if (ARR[var] == "" )		;if (ARR[var] == "" )
	:Check if index var has a value		:Check if index var has a value
	;for (init;test;incr)		;for (init;test;incr) { codeblock }
	:Loop~~, start~~ with init, as long as test is true, after ~~the statements~~ incr ~~num~~		:Loop. Start with init, as long as test is true, execute codeblock, after each loop execute incr.
	<syntaxhighlight lang=awk>		<syntaxhighlight lang=awk>
	for (num=10;num<=100:num++) {		for (num=10;num<=100:num++) {
Line 103:		Line 103:
	:Create a function. Parameters of the functions are local. All local variables should be defined as parameter to avoid overwriting a global variable. Overwriting a global variable on the other hand is a way to return results of the function.		:Create a function. Parameters of the functions are local. All local variables should be defined as parameter to avoid overwriting a global variable. Overwriting a global variable on the other hand is a way to return results of the function.
	;return <value>		;return <value>
	:End of function and give it a return value		:End of function and give it a return value

	==Magic==		==Magic==
	;gawk '{if (NR%3 == 0) {print p$0;p=""}else{p=p$0}}'		;gawk '{if (NR%3 == 0) {print p$0;p=""}else{p=p$0}}'
	:Combine lines per 3 (Basic code found on stackoverflow [https://stackoverflow.com/questions/3194534/joining-two-consecutive-lines-using-awk-or-sed])		:Combine lines per 3 (Basic code found on stackoverflow [https://stackoverflow.com/questions/3194534/joining-two-consecutive-lines-using-awk-or-sed])

Hdridder: /* Matching */

2020-07-27T12:27:32Z

Matching

← Older revision		Revision as of 12:27, 27 July 2020
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	==Matching==		==Matching==
	;/<pattern>/ {~~code~~}		;/<pattern>/ {codeblock}
	:Execute code if the current line matches <pattern>		:Execute code if the current line matches <pattern>

	;var ~ /<pattern>/ {~~code~~}		;var ~ /<pattern>/ {codeblock}
	:Execute code if var matches <pattern>		:Execute code if var matches <pattern>
	:!~ to negate the match		:!~ to negate the match

Hdridder: /* Basics */

2020-07-27T12:26:42Z

Basics

← Older revision		Revision as of 12:26, 27 July 2020
Line 2:		Line 2:
	==Basics==		==Basics==

	;awk -F"," -v VAR=<value> '{~~<code~~}'		;awk -F"," -v VAR=<value> '{codeblock}'
	:In awk: Use "," as field-separator and set VAR to <value>. With -v you can pass variables from the shell to the awk program.		:In awk: Use "," as field-separator and set VAR to <value>. With -v you can pass variables from the shell to the awk program.