Tag: awk

Using AWK to display the min the max and the average of a list

28 November 201828 November 2018 Fabien bash, Linux 1 Comment

awk is a extremely powerful tool !
i’m always surprised how much you can do with it.

My latest finding is pretty amazing.

Lets say you have a list of numbers , and you want to figure out the bigger number , the lower number , and the average of all the numbers in the list.

cat tmp.txt
40
10
25
35
11
2.2
99.5
100.1
1.5
5

you can use the following awk code to print minimum, maximum and average.

cat tmp.txt | awk '{if(min==""){min=max=$1}; if($1>max) {max=$1}; if($1<min) {min=$1}; total+=$1; count+=1} END {print "avg " total/count," | max "max," | min " min}'

The output is going to be :
avg 32.93 | max 100.1 | min 1.5

you can also use this code with decimal numbers

Use AWK to display x-th and y-th lines after a regex match

28 May 2017 Fabien Linux Leave a comment

In a script you might be interested to keep 2 or more lines after a regex match ,
the line that interest you are not always going to be right after the match ,
the first one might be X lines after the match and the second one Y lines afters the match

<item desc>
<name=Hammer>
<brand=none>
<weight=700>
<price=12> 
<location=A5H3>
<stock=56>

in this example , i’m interested in keeping the lines with the price and the number in stock
i’m going to use awk to search for item desc , and display the 4th line after the match, and 6th line.

awk '/item desc/{nr[NR+4]; nr[NR+6]}; NR in nr' filename

Extract values separated by character ( : , . – )

27 March 20177 May 2017 Fabien Linux Leave a comment

In a bash script if you find yourself with values presented that way

Hello:345:18.5:TRUE:000

you might want to keep only the second or third of this values that are separated by the : character

like always , in bash there is a lot of ways to accomplish that , but i like to use a one that use the AWK utility because it’s very easy to read and understand.

my list of value is contained in a var name $var let’s extract the third value which is 18.5

echo $var | awk -F':' '{print $3}'

Will return the value 18.5

but i can do some math operation in the utility, like :

echo $var | awk -F':' '{print $2-$3}'

this will return 326.5 the result of 345 – 18.5

awk is a fast and powerful text editor , there is a lot things you can do with it.