Delete all lines which don't have n characters before delimiter

$ awk '$1 ~ /^[[:xdigit:]]{6}$/' file
00107B  Cisco Systems, Inc
00906D  Cisco Systems, Inc
0090BF  Cisco Systems, Inc
000C6E  ASUSTek COMPUTER INC.
001BFC  ASUSTek COMPUTER INC.
001E8C  ASUSTek COMPUTER INC.
0015F2  ASUSTek COMPUTER INC.
001FC6  ASUSTek COMPUTER INC.
60182E  ShenZhen Protruly Electronic Ltd co.
F4CFE2  Cisco Systems, Inc
501CBF  Cisco Systems, Inc

This uses awk to extract the lines that contains exactly six hexadecimal digits in the first field. The [[:xdigit:]] pattern matches a hexadecimal digit, and {6} requires six of them. Together with the anchoring to the start and end of the field with ^ and $ respectively, this will only match on the wanted lines.

Redirect to some file to save it under a new name.

Note that this seems to work with GNU awk (commonly found on Linux), but not with awk on e.g. OpenBSD, or mawk.

---

A similar approach with sed:

$ sed -n '/^[[:xdigit:]]\{6\}\>/p' file
00107B  Cisco Systems, Inc
00906D  Cisco Systems, Inc
0090BF  Cisco Systems, Inc
000C6E  ASUSTek COMPUTER INC.
001BFC  ASUSTek COMPUTER INC.
001E8C  ASUSTek COMPUTER INC.
0015F2  ASUSTek COMPUTER INC.
001FC6  ASUSTek COMPUTER INC.
60182E  ShenZhen Protruly Electronic Ltd co.
F4CFE2  Cisco Systems, Inc
501CBF  Cisco Systems, Inc

In this expression, \> is used to match the end of the hexadecimal number. This ensures that longer numbers are not matched. The \> pattern matches a word boundary, i.e. the zero-width space between a word character and a non-word character.

---

For sorting the resulting data, just pipe the result trough sort, or sort -f if your hexadecimal numbers uses both upper and lower case letters

And for completeness, you can do this with grep too:

$ grep -E '^[[:xdigit:]]{6}\b' oui.txt 
00107B  Cisco Systems, Inc
00906D  Cisco Systems, Inc
0090BF  Cisco Systems, Inc
000C6E  ASUSTek COMPUTER INC.
001BFC  ASUSTek COMPUTER INC.
001E8C  ASUSTek COMPUTER INC.
0015F2  ASUSTek COMPUTER INC.
001FC6  ASUSTek COMPUTER INC.
60182E  ShenZhen Protruly Electronic Ltd co.
F4CFE2  Cisco Systems, Inc
501CBF  Cisco Systems, Inc
$ 

This extended grep expression searches for exactly 6 hex digits at the beginning of each line, followed immediately by a non-whitespace-to-whitespace boundary (\b).