What is the difference between /etc/rc.local and ~/.bashrc?

Question

This is a linux related problem. I have searched around but did not get a good explanation.

It seems to me that both file configure the setup when I log in, but is there any difference? I notice that there seems to be "some rule" in deciding what should go into two different files. For example, if I need to add a specific search path to $PATH, I should do it in ~/.bashrc. But if I decide to change some system setting, like

/sys/class/backlight

or

/sys/devices/cpu/cpu#/online

then I have to do this in /etc/rc.local, otherwise it will not work.

Is it because these configurations can not differ between users?

Thanks.

Answer 1

The difference is in when they are run and who they're running as when run i.e. rc.local is run on a change of run level and it runs as root. bashrc is bash specific and run on a non login shell as a particular user.

You can find a good explanation of rc.local here

The script /etc/rc.local is for use by the system administrator. It is traditionally executed after all the normal system services are started, at the end of the process of switching to a multiuser runlevel. You might use it to start a custom service, for example a server that's installed in /usr/local. Most installations don't need /etc/rc.local, it's provided for the minority of cases where it's needed.

and you can find what you need about bashrc

man bash

When an interactive shell that is not a login shell is started, bash reads and executes commands from ~/.bashrc, if that file exists. This may be inhibited by using the --norc option. The --rcfile file option will force bash to read and execute commands from file instead of ~/.bashrc.

There's more info on bashrc in this question...

https://superuser.com/questions/49289/what-is-the-bashrc-file