How can I change "which gcc" directory?

Question

gcc-4.8 is installed from build-essential.

I used gcc-4.8 to build gcc-4.7.4 from source, and put that 4.7 build in a folder called /AntonProj1

I have been able to change the symbolic link from the default gcc to the build in /AntonProj1 via

rm /usr/bin/gcc

ln -s /AntonProj1/bin/gcc /usr/bin/gcc

So, while I can find the correct version (4.7.4) by doing gcc-v, I am still linked to /usr/bin/gcc when I ask which gcc

When I try something like:

ln -s /AntonProj1/bin/gcc /AntonProj1/tmp/gcc

I am no longer able to get the correct version doing -v and it is still looking in /usr/bin/gcc when I ask which gcc (it actually throws bash: /usr/bin/gcc: No such file or directory)

How can I build a link to, for example, /AntonProj1/tmp/gcc so that I can use the gcc command to compile with my own build (gcc-4.7.4) instead of the default build?

Solution

This is what I did to fix things the way I was looking for them to be when I asked the question. I'm not sure if this is the best way; but, it's working for now:

Setting up symbolic links:

Remove existing links:

rm /usr/bin/gcc
rm /usr/bin/g++

Change name of default executibles because I want to run commands gcc and g++:

mv /AntonProj1/bin/gcc /AntonProj1/bin/gcc-4.7.4
mv /AntonProj1/bin/g++ /AntonProj1/bin/g++-4.7.4

Set new symbolic links:

ln -s /AntonProj1/bin/gcc-4.7.4 /AntonProj1/bin/gcc
ls -s /AntonProj1/bin/g++-4.7.5 /AntonProj1/bin/g++

Setting up PATH stuff:

export "PATH+=:/AntonProj1/bin"

While I'm not sure my method of setting up the path is ideal (it must not be since I have to add a path to any directory I'd like to run gcc or g++ from), this easy export appends the correct path to the end of whatever path is already set... I can imagine setting it up in a profile.d or something; but, for my purposes it's OK as it is.

Comments

[steeldriver]

which simply checks for executables on your PATH - it doesn't follow symlinks AFAIK. If you'd done readlink -f $(which gcc) you should have arrived at /AntonProj1/bin/gcc. However IMHO it would be cleaner to simply add /AntonProj/bin to the front of your PATH. It's not clear what you've done in the meantime to get /usr/bin/gcc: No such file or directory

[steeldriver]

BTW why did you install gcc-4.7.4 from source at all? it seems to be available in the repositories up until at least Ubuntu 16.10

[2xsaiko]

Kind of duplicate of askubuntu.com/questions/884576/…, maybe?

[Anton Rasmussen]

Ah, ok. I will check the PATH settings. Thanks! (And I installed it from source for a personal challenge. I'm trying to build 40 or so projects from source; but, I wanted to build gcc from source first so I could use that compiler to build the others...)

[Anton Rasmussen]

I discovered the way to do this permanently by setting the PATH by putting the export in the .profile file of the home directory: export "PATH=/AntonProj1/bin:/AntonProj1/share:/usr/local/sbin:/usr‌​/local/bin:/usr/sbin‌​:/usr/bin:/sbin:/bin‌​:/usr/games:/usr/loc‌​al/games" Of note here is that the new path should be at the beginning and not at the end...