AWK is a string manipulation program. Also programmable filter could be nice description.
I will use it in many of my scripts (especially in the rrd section), so i really need this tool.
You can download it from GNU and 3.1.3 is the current version.

I used ./configure -build=i586-pc-linux-gnu to configure it, and then a make to start the build.
The build only took a short time, and produced the gawk executable, which is about 770 KB in size. Also here stripping helps a lot, it shrinks the file to 277 KB.
Now if you look at the library dependencies, you see it needs libm.so.6 which is not yet available.

I will install gawk in /bin of the router image, and make a symbolic link called awk to it. Don't forget to copy libm.so.6 to the /lib directory of your image.