How to use nios2-corss compile tool in command line

You said you wanted to generate a .so - they are shared (dynamically loaded) libraries, and only apply to operating systems.

If you want to run compiler the IDE runs - in order to use your own makefiles (etc) - then just search for the directory they are in.

Something like:

find / -name '*nios2-elf-*' 2>/dev/null

is rather brutal, but should work.

Possibly they aren't installed with that prefix, so try looking for '*objdump*' instead.

Another alternative is to download the compiler and toolchain sources and build it youself. Details (and some compiler patches) are on the wiki.