Is is possible to join on unsorted files by a string? Don't want to sort because there is other text that is already in a good format.

File1 has this text string:
ABCD-123 FGH

File2 has this text string:
ABCD-123

I want to replace or join ABCD-123 in file 2 with ABCD-123 FGH in file 1.
Thank you.

What output would you want for that input?

Desired output would be for file2: ABCD-123 FGH. There are multiple ones though. So it would be:
ABCD-123 FGH and BCDE-345 JKL etc.
Not using sed because each instance is unique. Not sure if I'm being clear.

---------- Post updated at 03:24 PM ---------- Previous update was at 03:17 PM ----------

Just looked at my response, let me re-phrase it.
Desired output would be
ABCD-123 AAA
ABCD-456 BBB
ABCD-789 CCC
But these would appear in different places in the text file. Hope this is clearer and I do appreciate the help.

awk 'NR==FNR { A[$1]=1; next } $1 in A' file2 file1

syntax error Corona

Which syntax error?

Use nawk on solaris.

Maybe it should be:

awk 'NR==FNR { A[$1]=$1; next } $1 in A' file2 file1
                     ^
                  Missing