Match common IDs between two huge csv files [closed]

Answer 1

Can do this with standard join utility

file1.txt

1 a
2 b
3 c

file2.txt

1 002
2 x90
5 d07

join example

join -1 1 -2 1 -o 1.1,1.2,2.2 file1.txt file2.txt

here join is joining from file1.field1 to file2.field2 and outputting the fields specified with the -o flag

output

1 a 002
2 b x90