Using tr with a built in argument set

Question

I have a variable called charAlpha. It's purpose is to go through a text document and count alphabetic characters. I am trying to use tr and the built in [:alpha:] set to get just alphabetic characters. Then I am piping it through wc -c to count and get a number that is stored in charAlpha and later in the script it will echo the number stored in charAlpha. I hope I don't seem like I'm over explaining as I am trying to provide all information needed here. I have done that in the past and I am trying very hard not to do that! Thanks for any help!

I am using bash and editing my script within vim.

I set

charAlpha=`tr -dc [:alpha:] < | wc -c`

Then I get these two errors:

./filestats: command substitution: line 7: syntax error near unexpected token `|'
./filestats: command substitution: line 7: `tr -dc [:alpha:] < | wc -c'

Answer 1

The < in your pre-piped command isn't going to give tr any input. Hence, it's erroring on the pipe (it expects a source of input).

Answer 2

The < | part is probably your problem, you need a filename between them. Something like (it's normally recommended to use $(...) instead of`...`as well):

charAlpha=$(tr -dc [:alpha:] < $myFile | wc -c)