AWK column from a script param?

Question

I want to call awk from a bash script like this:

#!/bin/bash
awk -vFPAT='[^ ]*|"[^"]*"|\\[[^]]*\\]' '{ print $2 }' $1

I want $2 to be a number that I specify. So if the script is named get-log-column I'd like to be able to call it this way: get-log-column /var/log/apache2/access.log 4

In this example, 4 would be the column so the output would be column 4 from access.log.

In other words, if access.log looked like this:

alpha beta orange apple snickers 
paris john michael peace world

So the output would be:

apple
peace

Seems your `"` and `'` characters were not correctly pasted in your post, so edited them now, request you to be careful while pasting contents into the posts. — RavinderSingh13, Oct 25 '19 at 05:05
Possible duplicate of [How do I use shell variables in an awk script?](https://stackoverflow.com/questions/19075671/how-do-i-use-shell-variables-in-an-awk-script) — tripleee, Oct 25 '19 at 06:01
@tripleee, Hi sir, IMHO, I know it is duplicate of how to pass a shell variable into awk, since OP's question has to club it with printing as a specific column with value of variable that is the reason I haven't closed it as a dup. If I missed something then kindly do let me know I will make it dup ASAP then. — RavinderSingh13, Oct 25 '19 at 06:08

RavinderSingh13 · Accepted Answer · 2019-10-25T05:56:25.390

0

Could you please try following.

#!/bin/bash
var="$1"
awk -v FPAT='[^ ]*|"[^"]*"|\\[[^]]*\\]' -v varcol="$var" '{ print $varcol }' Input_file

Explanation:

Have created a shell variable var which will have $1 value in it. Where $1 value is the argument passed to script. Now in awk we can't pass shell variables directly so created 1 awk variable named var_col which will have value of var in it. Now mentioning $varcol will print column value from current line as per OP's question. $ means field number and varcol is a variable which has user entered value in it.

edited Oct 25 '19 at 05:56

answered Oct 25 '19 at 05:04

RavinderSingh13

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I could use an if statement ... but this seems clunky. – Oct 25 '19 at 13:54
@KevinSwindon, you mean you want to insert it as a new column? Sorry I am confused now. – RavinderSingh13 Oct 25 '19 at 13:56
I want to display column #4 if I use 4 in my command line argument. – Oct 26 '19 at 01:50
@KevinSwindon, then I need not to change anything in my script it will work. Create a new test script paste this code and run it like `./test.ksh 4` and it should fly then – RavinderSingh13 Oct 26 '19 at 02:05
@KevinSwindon, Could you please do let me know if this answer helped you? – RavinderSingh13 Oct 28 '19 at 07:41
1

Yes, thank you very much Ravinder! Much appreciated! – Oct 29 '19 at 04:44

Jotne · Answer 2 · 2019-10-25T10:13:36.017

0

This may work

#!/bin/bash
awk -v var="$1" -v FPAT='[^ ]*|"[^"]*"|\\[[^]]*\\]' '{ print $var }' $1

See this on how to use variable from shell in awk How do I use shell variables in an awk script?

edited Oct 25 '19 at 10:13

answered Oct 25 '19 at 05:05

Jotne

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@oguzismail Thanks, cut and past from OP original post that was wrong. – Jotne Oct 25 '19 at 10:14

AWK column from a script param?

2 Answers2