How to count the number of characters in a line, except a specific character?

GNU awk solution:

awk -v FPAT='[^N[:space:]]' '{ print NF }' file

FPAT='[^N[:space:]]' - the pattern defining a field value (any character except N char and whitespace)

The expected output:

awk '{ gsub("[ N]",""); print length() }'

assuming that count is needed for each line other than space character and N

$ perl -lne 'print tr/N //c' ip.txt 
1
1
1
0
1
2
2

return value of tr is how many characters were replaced
c to complement the set of characters given
Note the use of -l option, strips newline character from input line to avoid off-by-one error and also adds newline character for the print statement

A more generic solution

perl -lane 'print scalar grep {$_ ne "N"} @F' ip.txt

-a option to automatically split input line on white-spaces, saved in @F array
grep {$_ ne "N"} @F returns array of all elements in @F which doesn't match the string N
- regex equivalent would be grep {!/^N$/} @F
use of scalar will give number of elements of the array

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