Number of fields returned by awk

Question

Is there a way to get awk to return the number of fields that met a field-separator criteria? Say, for instance, my file contains

a b c d

so,

Answer 1

If you would like to know the set of all the numbers of fields in a multiline content you can run:

X | awk '{print NF}' | sort -n | uniq

being X a command that outputs content in the standard output: cat, echo, etc. Example:

With file.txt:

a b
b c
c d
e t a
e u

The command cat file.txt | awk '{print NF}' | sort -n | uniq will print:

2
3

And with file2.txt:

a b
b c
c d
e u

The command cat file2.txt | awk '{print NF}' | sort -n | uniq will print:

2