csvfill

usage: csvfill [-1 col1] [-2 col2] [-d delim] file1 [file2]

Fill empty cells ("", NA, NaN) in file1 with values from file2,
matching rows by their ID column, and print the result.
Existing values are never overwritten.
If file2 is omitted, it is read from standard input.

  -1 col1    ID column in file1, 1-based (default: 1)
  -2 col2    ID column in file2, 1-based (default: 1)
  -d delim   field delimiter (default: ,)
  -h         show this help

Details can be found in the man page.

Install and uninstall

Needs sudo/doas:

make install
make remove

Bugs

• Can't handle embedded new lines in fields.