I wanted to get a return value of 1 if the first two lines exist in the file1.txt.
The awk statement is working for the 3rd line but not for the first two lines. The NF works if I run it from the command line but it doesn't return 1 when I put it in the same line?

awk -F[.] 'NF !~2||$1!~/^[0-9]+$/||$2!~/^[a-zA-Z0-9]+$/{exit 1}' file1.txt

cat file1.txt
192.168.1.1 192.168.1.2
192.168.1.3
192.168.1.4 host100

I appreciate your help!

Maybe I didn't make my question clear?
I'm having trouble getting a return code of 1 if the file has:

- less than one field or greate than 2 fields

- if the file has blank lines

- if the file has numbers only in both of the two fields.

and return only 0 if the file has two fields where the first field is only numbers and the second field is a mix of characters and numbers.

awk -F[.] 'NF !~2||$1!~/^[0-9]+$/||$2!~/^[a-zA-Z0-9]+$/{exit 1}' file1.txt

cat file1.txt
192.168.1.1 192.168.1.2
192.168.1.3
192.168.1.4 host100