Switch GCC, G ++, and gfortran versions in Ubuntu

Switch GCC, G ++, and gfortran versions in Ubuntu

Step 1: use which gcc, which g ++, and which gfortran to view the location. My result is/usr/bin/gcc; /usr/bin/g ++ and/usr/bin/gfortran

Part 2: first, let's take a look at the gcc commands installed in your Ubuntu: ls/usr/bin/gcc *-l;

Gcc/g ++ in ubuntu 12.04 is 4.6. We will downgrade the default system to 4.4.

$ Sudo apt-get install gcc-4.4

$ Sudo update-alternatives -- install/usr/bin/gcc/usr/bin/gcc-4.4 40

(Here "40" is the priority. The higher the value, the higher the priority)

$ Sudo update-alternatives -- install/usr/bin/gcc/usr/bin/gcc-4.6 60

(The built-in priority is set to 60 and higher)

Select the default gcc

$ Sudo update-alternatives -- config gcc

Selection Path Priority Status

------------------------------------------------------------

* 0/usr/bin/gcc-4.6 60 auto mode

1/usr/bin/gcc-4.4 40 manual mode

2/usr/bin/gcc-4.6 60 manual mode

The highest priority is used by default,

Select 1 here.

Next, perform the same steps in g ++.

$ Sudo apt-get install g ++-4.4

$ Sudo apt-get install g ++-4.4-multilib

 

$ Sudo update-alternatives -- install/usr/bin/g ++-4.4 40

$ Sudo update-alternatives -- install/usr/bin/g ++-4.6 60

$ Sudo update-alternatives -- config g ++

Selection Path Priority Status

------------------------------------------------------------

* 0/usr/bin/g ++-4.6 60 auto mode

1/usr/bin/g ++-4.4 40 manual mode

2/usr/bin/g ++-4.6 60 manual mode

Select 1.

If you want to change to a later version

Update-alternatives -- config command switch!

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