Installing Older or Multiple GCC Versions on Ubuntu 14.04 Trusty

In trying to port my company's software from CentOS 6 to Ubuntu 14.04, it became apparent that I may need to modify the Ubuntu build environment (don't ask... much easier than changing the 15 years worth of software... trust me). Just to give you some idea, the software began in the early 90s with GCC v2 on 32 bit platforms (target was CentOS 4). It then evolved to CentOS 5 and then 6, all the way up though GCC v3.4. To support running our software on the latest hardware, Ubuntu 14.04 LTS release became our desired target.

Ubuntu 14.04 comes with GCC v4.8. The last version of Ubuntu to include GCCv3.4 was Hardy. So we'll need to include that in our repo source list. The problem here was that all the posts I found referenced incorrect old-releases addresses, so here is what I found that worked...

Note, if you haven't done so already, be sure to install the build stuff:

apt-get install build-essential

First add the old repos to the sources file, so apt can find what we need:

vim /etc/apt/sources.list 

deb http://old-releases.ubuntu.com/ubuntu hardy universe

deb-src http://old-releases.ubuntu.com/ubuntu hardy universe

Then get the latest repo data:

apt-get update

Then install the older GCC:

apt-get install gcc-3.4

apt-get install g++-3.4 

Next, we'll need to configure multiple compilers (note, the last number is just an arbitrary priority):

update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.8 20

update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-3.4 10

After that, just select which compiler you want to use, before you go to compile:

update-alternatives --config gcc

I also found that I had to update the linker's symbolic link, as it was pointing to a non-existent library file (/lib/libgcc_s.so.1):

ln -sfn /lib/x86_64-linux-gnu/libgcc_s.so.1 /usr/lib/gcc/x86_64-linux-gnu/3.4.6/libgcc_s.so

Fix Google Chrome Crashes by Increasing Open Files Limit in Linux Mint

I found myself frequently having Google Chrome crash when opening many tabs across several windows (don't judge me) on my Linux Mint 17 Cinnamon desktop.

Upon further investigation, I found that Chrome was throwing some error about too many open files.

 ~ tail -f ~/.xsession-errors 

The error, I can't remember, but was something in shared_memory_posix about /dev/shm/.com.google.Chrome and Too many open files.

If you look at the configured default open limit, it's very low (like 1024).

~ ulimit -n

The fix (so far, so good) seems to be editing /etc/security/limits.conf and adding the following line at the end of the file:

* hard nofile 65535

* soft nofile 65535

Reboot the machine, and should be all good.

Note: I saw several people modifying their fs.file-max settings, but that made Cinnamon not even want to load and played hardcore shenanigans with my machine, overall.