how to save arithmetic expression into a variable in shell?

Question

I want to save the number of lines minus 2 into a shell variable.

I have tried this:

eval a = wc -l  meny1.xml | awk '{print $1}

tail a-2 meny1.xml >> tmp

for saving the number of line of a file and then decrease it by 2.

but it doesn't do the trick

how should I write this?

Answer 1

You could try something like:

$ export count=$((`wc -l < myfile` - 2))
$ echo $count
2
$ wc -l file
4

Answer 2

You can try something like

$ a=$(wc -l file | awk '{print $1-2}')
$ echo $a
3

$ wc -l file
5 file