How to use grep/awk/unix to match all lines from one file in another file, even if they are duplicates

Question

I'm trying to retrieve the the matching lines from a file, however the file that has the "index" or list of matches to retrieve also has duplicate entries and I want to print out the duplicates as well.

Example:

File 1 (index file or list of strings to match)

abc
tgf
abc
ggg
aaa
fff

File 2 (what I want to retrieve for each of the matches in file 1)

Fred   1   3   abc
Amy    2   4   ggg
Dan    5   6   tgf
Mike   9   1   fff
Steve  2   1   aaa

My desired result would be (order is not important, just that I match every line):

Fred   1   3   abc
Dan    5   6   tgf
Fred   1   3   abc
Amy    2   4   ggg
Steve  2   1   aaa
Mike   9   1   fff

I'm familiar and have tried grep as follows, but it does not print the duplicate entries.

grep -Fwf file1.txt file2.txt

Fred   1   3   abc
Amy    2   4   ggg
Dan    5   6   tgf
Mike   9   1   fff
Steve  2   1   aaa

Answer 1

Via awk

awk 'NR==FNR{A[$4]=$0;next}{print A[$1]}' file2.txt file1.txt

Or sorted output via join:

join -o 2.1 2.2 2.3 2.4 -2 4 <(sort file1.txt) <(sort -k4 file2.txt)