I have a relatively small space delimited file which looks like this (but with many columns and rows):file1:Entry1abcdAnd another huge tab delimited file with many duplicated entries per row like this:file2:value       ID1   ID2   1      a    aaaa11      a    aaaa21      b    bbbb11      b    bbbb21      b    bbbb31      d    aaaa4I am trying to first print a tab delimited file of the same size as file1 specifying matches between each entry in file1 and ID1 field (column 2) in file2 like this this is a separate question:Entry1abNoMatchdAnd also print a merged tab delimited file with the values of file1 and file2, this time with repeated entries if there are in file2, but keeping the NoMatch as well, like this:value       ID1   ID2   1      a    aaaa11      a    aaaa21      b    bbbb11      b    bbbb21      b    bbbb3NoMatch NoMatch NoMatch1      d    aaaa4I have tried using the join command to give me a NoMatch message:join -a1 -e NoMatch <(awk -F ' ' '{print $0}' file1.txt |tail -n +2|sort -k1,1) <(cat file2 | sort -k1,1) > out.txtbut I must be doing something wrong because this prints all of file1 for example, but if there is no match in file2 the rest of the fields are blank (so no message NoMatch appears), can you please help me understand what I am doing wrong? Thanks so much!#Thank you gilles, I can't seem to answer your comment as I just registered...What you suggested: join -a1 -e NoMatch -11 -22 --header -o2.1,2.2,2.3 file1 file2solved the second query Output2, thank you! Can I ask how I can get the first Output1, with the same lines as the file1? Thanks again!!With don_crissti's help, I can get the second output like this:paste -d'\t' file2 <(awk 'FNR==NR{seen[$1]++; next}  {(FNR==1 || ($1 in seen)) || $1=NoMatch};1'  file2  file1)
Merge and print matching and non matching values between a smaller file and a huge file
bash;text processing;join