Extract info in loops from specific column based on list of input

Question

I have fileA and fileB.

fileA is storing a list of names I wanted to extract from the second column of fileB.

fileA:

QW123
BH876
PR009

fileB:

MJ194   PR009   100
PR009   IJ940   78
JG948   BH448   58

desire output:

MJ194   PR009   100
JG948   BH448   58

I am trying it with the command below but none of them worked. Wondering what is left out in between the codes.

• for i in $(cat fileA); do awk '$2=="$i"' fileB; done
• for i in $(cat fileA); do awk -v 'i="$i"' '$2=="i"' fileB; done

Any help would be much appreciated.

Answer 1

Your second attempt would "work" if you remove extraneous quoting:

for i in $(cat fileA); do awk -v i="$i" '$2==i' fileB; done    # but don't do this

However, if you are determined to use a shell loop, it would be better to use while:

while IFS= read -r i; do awk -v i="$i" '$2==i' fileB; done < fileA    # don't do this either

Better would be to avoid the shell loop altogether:

awk 'NR==FNR{a[$1]; next} $2 in a' fileA fileB

See also:

• How to loop over the lines of a file?

• Why is using a shell loop to process text considered bad practice?