#111 can't run fileless awk commands in shell-command

something\tsomethingelse\tend
something new\tsomethingelsemnew\tendnew
something new new\tsomethingelsenewnew\tendnewnew

Imagine you have some data like this: ``` something\tsomethingelse\tend something new\tsomethingelsemnew\tendnew something new new\tsomethingelsenewnew\tendnewnew ``` and you need to get the first column and last column. Since you're an expert awk(1) programmer you know that this is a simple `awk '{ print $1 $3 }'`. However, if you selected this region and ran it in ait, it won't work. This is very sad and will cause depression. The issue is due to the $ escaping that happens around shell.c:354.