UNIX for Dummies Questions & Answers

Hello, I have a problem comparing two files, both .csv. One file, let's call it files.csv, contains a list of thousands of file names for models of molecules that have made it through an optimization process. The other file, formulas.csv, contains file names for the same kind of models, and has another column for the chemical formula of these molecules. This is valuable information that I would like to have to put in Excel spreadsheets, amongst other things. The problem is, formulas.csv contains all of the files in file.csv, but also many additional molecules that I have no need for. All the molecules I need are in files.csv. Thus, my question is, can I possibly compare the two files, and then delete any molecules from formulas.csv that are not contained in files.csv? If possible, I would like to do this in VIM, because I am fairly comfortable in that program, but I am not sure it is possible. So, any shell or Perl scripts that would do the job would also be greatly appreciated.

My explanation may have been vague and long winded, so here's an example:
files.csv
C5029663
C50313718
C503208
C50337014
C50338802
........

formulas.csv
C5029663, C4H7IO2
C50313718, C15H32O
C503208, C2H2FN
C503275, C2H4N2
C50337014, C9H18O
C503388, C2Cl4O2
C50338802, C6H10
........

The bolded lines in formulas.csv have no corollary in files.csv, and I would like to remove them. Any help would be appreciated. Thanks!

Try:

Code:

awk -F, 'NR==FNR{a[$1]=1;next}$1 in a' files.csv formulas.csv > filtered.csv

PS. Please use code tags for sample data: https://www.unix.com/how-post-unix-li...code-tags.html

Thank you very much for you help Bartus, and I will certainly use code tags in the future.