How to quote a shell variable in a TCL-expect string

Question

I'm using the following awk command in an expect script to get the gateway for a particular destination

route | grep $dest | awk '{print $2}'

However the expect script does not like the $2 in the above statement.

Does anyone know of an alternative to awk to perform the same function as above? ie. output 2nd column.

Answer 1

You can use cut:

route | grep $dest | cut -d \  -f 2

That uses spaces as the field delimiter and pulls out the second field

Answer 2

To answer your Expect question, single quotes have no special meaning to the Tcl parser. You need to use braces to protect the body of the awk script:

route | grep $dest | awk {{print $2}}

And as awk can do what grep does, you can get away with one less process:

route | awk -v d=$dest {$0 ~ d {print $2}}