awk issue inside for loop-CodePudding

I have many files with different names that end with txt.

rtfgtq56.txt
fgutr567.txt
..

So I am running this command

for i in *txt
do
  awk -F "\t" '{print $2}' $i | grep "K" | awk '{print}' ORS=';' | awk -F "\t" '{OFS="\t"; print $i, $1}' > ${i%.txt*}.k
done

My problem is that I want to add the name of every file in the first column, so I run this part:

awk -F "\t" '{OFS="\t"; print $i, $1}' > ${i%.txt*}

$i means the file that are in the for loop, but it did not work because awk can't read the $i in the for loop. Do you know how I can solve it?

CodePudding user response：

You want to refactor eveything into a single Awk script anyway, and take care to quote your shell variables.

for i in *.txt
do
    awk -F "\t" '/K/{a = a ";" $2}
      END { print FILENAME, substr(a, 1) }' "$i" > "${i%.txt*}.k"
done

... assuming I untangled your logic correctly. The FILENAME Awk variable contains the current input file name.

More generally, if you genuinely want to pass a variable from a shell script to Awk, you can use

awk -v awkvar="$shellvar" ' .... # your awk script here
    # Use awkwar to refer to the Awk variable'

Perhaps see also useless use of grep.

CodePudding user response：

Using the -v option of awk, you can create an awk Variable based on a shell variable.

awk -v i="$i" ....

Another possibility would be to make i an environment variable, which means that awk can access it via the predefined ENVIRON array, i.e. as ENVIRON["i"].