Hi Steven,
Steven W. Orr wrote:
On 11/02/09 04:28, quoth Suvayu Ali:
Hi Steven,
On Sunday 01 November 2009 09:32 PM, Steven W. Orr wrote:
On 10/31/09 03:39, quoth Jonathan Ryshpan:
IT IS WRONG to set environment variables in your .bashrc unless you
really
know what you're doing. Most people don't. IT IS WRONG to have to run a
terminal emulator program with the idea that it should be a login
shell. ALL
PROGRAMS use the environment, not just terminal emulators. If you log
in then
your environment should be defined.
What is your comment on the method I posted, have your .bash_profile
source your .bashrc ? That way you have a consistent environment every
time, irrespective of whether I am at an xterm or VT or simply running
some GUI app from a menu or icon. (I am of course assuming my desktop
environment sources my .bash_profile, as it should, when I login :) )
Would you say that is a proper way to do things?
It is correct that the .bash_profile should source in the .bashrc but it is
wrong for a terminal emulator to be executed as a login process to account for
gdm's deficiency.
First of all your .bash_profile should source in your .bashrc or else you
won't get any of your bashrc content in your login process. Starting a login
process must run your .bash_profile and starting a sub shell process must run
the .bashrc This means that the .bashrc must be run by the .bash_profile or
else the login process will never get any of your local aliases, functions and
variable settings.
This confuses a lot of people:
* When you log in, the login process must define the environment. This is done
by sucking in the ~/.bash_profile after the /etc/profile
* The ~/.bashrc is sucked in automatically only by sub shells. To get bashrc
content added to your login shell, the ~/.bash_profile must pull in the ~/.bashrc
* The /etc/bashrc is not run by the system. The user is responsible for doing
this himself. In your ~/.bashrc should be a line that says:
. /etc/bashrc
All of what I describe above is how things should be done, but it is *wrong*
for the gdm login process to not run the correct files for you in the first
place. That is why I have showed you how to go about the process of fixing it
properly. You need to see about pulling in the /etc/profile and
~/.bash_profile from the /etc/X11/xinit system. You will *probably* be able to
add a file (maybe call it) /etc/X11/xinit/xinitrc.d/00_bash_init.sh It should
say something like what I mentioned above. I recommend *not* making it
executable even though all of the files in /etc/X11/xinit/xinitrc.d are. This
just confuses people more. Sourced files are not executed; they are read into
a current shell.
I know what you mean. I have to do a lot of data analysis at the
university and we use a really complex framework written in C++, called
ATHENA. To ensure all the various sub-packages /behave/ with each other
we use environment variables controlled with lots of sourced shell
scripts. Its really amazing and extremely elegant way of controlling how
things behave. :)
If you do it wrong then you will be putting a crappy bandage on a system that
is capable of much elegance. The whole point of environment variables is to
define what *all* child processes will inherit. Look at the env command. It's
not about what you see as being used by bash. It's about what the getenv(3)
and setenv(3) runtime calls make available to all child processes,
irrespective of what language they are written in. The environment is agnostic
about linguistics.
Let's look at an example. In my environment, I define XFILESEARCHPATH and
XUSERFILESEARCHPATH. If I do it then my applications will start up with the
correct set of resources. If I don't then they will not. But what I will not
accept is that I must start my applications from a terminal emulator that was
artificially started with a --login option. That's just silly. If I want to
create a button that run my application then I expect that button to be
running in the proper environment that has those variables set to the values
that I have defined.
Make sense?
Thank you for this entire reply Steven. All the subtleties you mentioned
makes a lot of sense. Following these simple rules makes everything work
consistently whether its being run from an xterm, VT or from a button on
my desktop. I'll try to go over what you said again and try to keep
those in mind while investigating any future issues and will definitely
try to include any such information in any bug report I contribute to.
Thanks a lot, learned a lot. :)
--
Suvayu
Open source is the future. It sets us free.
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