I need to install a cross-compiler for the Pi and I'm following https://xmleye.wordpress.com/2017/10/17/running-uml-rt-models-on-a-raspberry-pi-based-rover/#comments because it's really similar to my project. I'm new to Linux and was trying to fix this error but I am stuck.

tt@ReNiS ~/crosstool-ng $ sudo apt-get install gperf bison flex makeinfo texinfo help2man
Reading package lists... Done
Building dependency tree       
Reading state information... Done
E: Unable to locate package makeinfo

After I got this, I ran sudo apt install texinfo to install makefile. I can now find it, but I still get the same result.

tt@ReNiS $ which makeinfo
/usr/bin/makeinfo

I also ran this but it's still not working.

sudo apt update

System info: Linux Mint 18.3 Cinnamon 64bit. kernel 4.19 Can someone help? Thanks!