I am querying one file with the other file and have them as following:
File1:
Angela S Darvill| text text text text
Helen Stanley| text text text text
Carol Haigh S|text text text text .....
File2:
Carol Haigh
Helen Stanley
Angela Darvill
This command:
awk 'NR==FNR{_[$1];next} ($1 in _)' File2.txt File1.txt
returns lines that overlap, BUT doesn’t have a strict match. Having a strict match, only Helen Stanley should have been returned.
How do you restrict awk on a strict overlap?
With your shown samples please try following. You were on right track, you need to do 2 things, 1st: take whole line as an index in array a while reading file2.txt and set field seapeator to | before awk starts reading file1
awk -F'|' 'NR==FNR{a[$0];next} $1 in a' File2.txt File1.txt
Command above doesn’t work for me (I am on Mac, don’t know whether it matters), but
awk 'NR==FNR{_[$0];next} ($1 in _)' File2.txt. FS="|" File1.txt
worked well
You can also use grep to match from File2.txt as a list of regexes to make an exact match.
You can use sed to prepare the matches. Here is an example:
sed -E 's/[ \t]*$//; s/^(.*)$/^\1|/' File2.txt
^Carol Haigh|
^Helen Stanley|
^Angela Darvill|
...
Then use process with that sed as an -f argument to grep:
grep -f <(sed -E 's/[ \t]*$//; s/^(.*)$/^\1|/' File2.txt) File1.txt
Helen Stanley| text text text text
Since your example File2.txt has trailing spaces, the sed has s/[ \t]*$//; as the first substitution. If your actual file does not have those trading spaces, you can do:
grep -f <(sed -E 's/.*/^&|/' File2.txt) File1.txt
Ed Morton brings up a good point that grep will still interpret RE meta-characters in File2.txt. You can use the flag -F so only literal strings are used:
grep -F -f <(sed -E 's/.*/&|/' File2.txt) File1.txt