awk output to variable

Question

[Dd])   
echo"What is the record ID?" 
read rID
numA= awk -f "%" '{print $1'}< practice.txt

I cannot figure out how to set numA = to the output of the awk in order to compare rID and numA. numA is equal to the first field of a txt file which is separated by %. Any suggestions?

karakfa · Answer 1 · 2016-04-03T23:58:29.980

0

this is the correct syntax.

numA=$(awk -F'%' '{print $1}' practice.txt)

however, it will be easier to do comparisons in awk by passing the bash variable in.

awk -F'%' -v r="$rID" '$1==r{... do something ...}' practice.txt

since you didn't specify any details it's difficult to suggest more...

to remove rID matching line from the file do this

awk -F'%' -v r="$rID" '$1!=r' practice.txt > output

will print the lines where the condition is met ($1 not equal to rID), equivalent to deleting the ones which are equal. You can mimic in place replacement by

awk ... practice.txt > temp && mv temp practice.txt

where you fill in ... from the line above.

edited Apr 03 '16 at 23:58

answered Apr 03 '16 at 23:09

karakfa

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it is basically a bash script that edits a .txt file. – jonathanw416 Apr 03 '16 at 23:35
devil is in the details. You'll get more help and better suggestions if you can specify a simple output and expected output. – karakfa Apr 03 '16 at 23:36
it has several fields per line, and this specific function removes the line specified by the user from the practice.txt file – jonathanw416 Apr 03 '16 at 23:37

score 0 · Answer 2 · answered Apr 03 '16 at 23:15

You can capture the output of any command in a variable via command substitution:

numA=$(awk -F '%' '{print $1}' < practice.txt)

Unless your file contains only one line, however, the awk command you presented (as corrected above) is unlikely to be what you want to use. If the practice.txt file contains, say, answers to multiple questions, one per line, then you probably want to structure the script altogether differently.

score 0 · Answer 3 · answered Apr 03 '16 at 23:20

0

You don't need to use awk, just use parameter expansion:

numA=${rID%%\%*}

answered Apr 03 '16 at 23:20

Ell

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score 0 · Answer 4 · answered Apr 04 '16 at 06:08

Try using

$ numA=`awk -F'%' '{ if($1 != $0) { print $1; exit; }}' practice.txt`

From the question, "numA is equal to the first field of a txt file which is separated by %"

-F'%', meaning % is the only separator we care about
if($1 != $0), meaning ignore lines that don't have the separator
print $1; exit;, meaning exit after printing the first field that we encounter separated by %. Remove the exit if you don't want to stop after the first field.

awk output to variable

4 Answers4