Enviroment variables in .bash_profile

TL_CLD · 07-21-2009, 04:08 AM

Hey all,

I have a weird problem. In my /~/.bash_profile file I have this:

Code:

ADA_PROJECT_PATH=$ADA_PROJECT_PATH:/usr/local/lib/gnat
export ADA_PROJECT_PATH

I boot to runlevel 3. When I log in, and echo $ADA_PROJECT_PATH, I get this:

Code:

:/usr/local/lib/gnat

Which is exactly what I should get.

But if I then run startx (I use KDE), and start a Konsole and echo $ADA_PROJECT_PATH again, I get this:

Code:

:/usr/local/lib/gnat:/usr/local/lib/gnat

What the?? Why are there now two paths??

Booting to runlevel 4 changes nothing. As soon as KDE is up and running, I have multiple paths, instead of just the one I'm actually exporting in .bash_profile.

Hopefully this is just some minor thing I'm not doing right, but it's completely eluding me.

I hope someone can help.

/Thomas

dahongpalay · 07-21-2009, 04:22 AM

i think it should be;

Code:

ADA_PROJECT_PATH=/usr/local/lib/gnat
export ADA_PROJECT_PATH

TL_CLD · 07-21-2009, 04:47 AM

Quote:

Originally Posted by dahongpalay

i think it should be;

Code:

ADA_PROJECT_PATH=/usr/local/lib/gnat
export ADA_PROJECT_PATH

Yes, but how can I then preserve additional paths added to the variable?

Code:

ADA_PROJECT_PATH=$ADA_PROJECT_PATH:/usr/local/lib/gnat
ADA_PROJECT_PATH=$ADA_PROJECT_PATH:/some/other/path
ADA_PROJECT_PATH=$ADA_PROJECT_PATH:/and/a/third/path

Without the $ADA_PROJECT_PATH part, that will fail, and only the last path is added to ADA_PROJECT_PATH.

TL_CLD · 07-21-2009, 05:05 AM

Quote:

Originally Posted by dahongpalay

i think it should be;

Code:

ADA_PROJECT_PATH=/usr/local/lib/gnat
export ADA_PROJECT_PATH

I've just confirmed this: If I dump the $ADA_PROJECT_PATH: part, then the paths set in /etc/profile are deleted/written over.

It is a mystery to me why my bash_profile files are being sourced more than once, and why it appears only to happen when i start X.

onebuck · 07-21-2009, 07:58 AM

Hi,

Quote:

excerpt from 'man bash';

When bash is invoked as an interactive login shell, or as a non-interactive shell with the --login option, it first reads and executes commands from the file /etc/profile, if that file exists. After reading that file, it looks for ~/.bash_profile, ~/.bash_login, and ~/.profile, in that order, and reads and executes commands from the first one that exists and is readable. The --noprofile option may be used when the shell is started to inhibit this behavior.

When a login shell exits, bash reads and executes commands from the file ~/.bash_logout, if it exists.

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.

Try placing your path in '.bashrc'.

You could setup a .bashrc & .bash_profile for your user;

Code:

sample .bash_profile;

~$ cat .bash_profile
# .bash_profile
#08-30-06 12:21 
#
# Source .bashrc
if [ -f ~/.bashrc ]; then
        . ~/.bashrc
fi

Code:

sample .bashrc;
:~$ cat .bashrc

#.bashrc
#08-30-06 12:20 

# Add bin to path

export PATH="$PATH:/sbin:/usr/sbin:$HOME/bin"

#export PATH="$PATH:$HOME/bin"

# Dynamic resizing
shopt -s checkwinsize

# Custom prompt
#PS1='\[\033[01;32m\]\u@\h\[\033[00m\]:\[\033[01;34m\]\w\[\033[00m\]\$ '

#08-29-06 11:40 gws

if [ `id -un` = root ]; then
   PS1='\[\033[1;31m\]\h:\w\$\[\033[0m\] '
 else
   PS1='\[\033[1;32m\]\h:\w\$\[\033[0m\] '
fi

#
# Add color
eval `dircolors -b`

# User defined aliases
alias cls='clear'
alias clls='clear; ls'
alias ll='ls -l'
alias lsa='ls -A'
alias lsg='ls | grep'
alias lsp='ls -1 /var/log/packages/ > package-list'
alias na='nano'
alias web='links -g -download-dir ~/ www.google.com'

#08-29-06 11:50

#To clean up and cover your tracks once you log off
#Depending on your version of BASH, you might have to use
# the other form of this command
   trap "rm -f ~$LOGNAME/.bash_history" 0

#The older KSH-style form
#   trap 0 rm -f ~$LOGNAME/.bash_history

grissiom · 07-21-2009, 01:10 PM

I just wonder whether Konsole is a login shell or not. I remember I have had such problem in KDE3...

jmacloue · 07-21-2009, 01:13 PM

Well, .bash_profile is executed after you log in to the system - that's when you enter your username and password at the console _and_ when you start your shell in Konsole as a login shell (seems it is so by default - can't check though, I don't use KDE).

So, when you initially log in to the system, .bash_profile sets ADA_PROJECT_PATH to ":/usr/local/lib/gnat". Then you fire up KDE and Konsole executes bash again - but in this case ADA_PROJECT_PATH is already in your environment so it gets expanded and the value is "duplicated".

On the other hand, .bashrc is executed every time the bash is run so moving your ADA_PROJ_PATH routine there will duplicate the variable as well. If it really creates any problems you can try smth like that:

Code:

[ -z "$ADA_PROJECT_PATH_SET"] && export ADA_PROJECT_PATH=$ADA_PROJECT_PATH:/usr/local/lib/gnat
export ADA_PROJECT_PATH_SET=1

in your .bash_profile. This will set ADA_PROJECT_PATH_SET variable upon initial login and then bash invoked from Konsole will skip the assigment.

But better way will be to make Konsole invoke bash in regular, not "login shell" mode.

onebuck · 07-21-2009, 02:21 PM

Hi,

Sorry but the '/etc/profile' will be used if it exists so when you login initially when bash is invoked then the use of ~/.bash_profile, ~/.bash_login, and ~/.profile is read until something that is read and executable then that is executed;

Quote:

excerpt from 'man bash';

When bash is invoked as an interactive login shell, or as a non-interactive shell with the --login option, it first reads and executes commands from the file /etc/profile, if that file exists. After reading that file, it looks for ~/.bash_profile, ~/.bash_login, and ~/.profile, in that order, and reads and executes commands from the first one that exists and is readable. The --noprofile option may be used when the shell is started to inhibit this behavior.

When a login shell exits, bash reads and executes commands from the file ~/.bash_logout, if it exists.

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.

A user should setup the '.bashrc' whenever the interactive is not a login shell.

That's one of the advantages of using a '~/.bash_profile' that contains conditional tests to execute the '~/.bashrc'.

TL_CLD · 07-22-2009, 01:00 AM

Quote:

Originally Posted by jmacloue

Well, .bash_profile is executed after you log in to the system - that's when you enter your username and password at the console _and_ when you start your shell in Konsole as a login shell (seems it is so by default - can't check though, I don't use KDE).

So, when you initially log in to the system, .bash_profile sets ADA_PROJECT_PATH to ":/usr/local/lib/gnat". Then you fire up KDE and Konsole executes bash again - but in this case ADA_PROJECT_PATH is already in your environment so it gets expanded and the value is "duplicated".

On the other hand, .bashrc is executed every time the bash is run so moving your ADA_PROJ_PATH routine there will duplicate the variable as well. If it really creates any problems you can try smth like that:

Code:

[ -z "$ADA_PROJECT_PATH_SET"] && export ADA_PROJECT_PATH=$ADA_PROJECT_PATH:/usr/local/lib/gnat
export ADA_PROJECT_PATH_SET=1

in your .bash_profile. This will set ADA_PROJECT_PATH_SET variable upon initial login and then bash invoked from Konsole will skip the assigment.

This looks like a very neat and tidy way of fixing a somewhat annoying issue. Thank you.

Quote:

Originally Posted by jmacloue

But better way will be to make Konsole invoke bash in regular, not "login shell" mode.

AFAIK that is standard behavior for Konsole. I think you have to explicitly tell it to start as a login shell (the --ls option), if that's what you want.

So the only other thing I can come up with, is that it happens when X and/or KDE is started.

/Thomas