I'm trying to build GNU grep, and when I run make, I get:

[snip]
/bin/bash: line 9: makeinfo: command not found

What is makeinfo, and how do I get it?

(This is Ubuntu, if it makes a difference)

In (at least) Ubuntu when using bash, it tells you what package you need to install if you type in a command and its not found in your path. My terminal says you need to install 'texinfo' package.

sudo apt-get install texinfo