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Bash shells with different environment variables

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http://unix.stackexchange.com – I want to somehow enter a different bash shell with some altered environment variables. For example, if I run script bfin.sh and it contains something like export PATH=/home/me/bfin2012:$PATH I want it to create a bash shell with this changed variable. How to do this? (HowTos)

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Submitted by missing on 10/16/2012

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Hi everyone,

well I am using Linux some years, but since I built a LFS, I feel noobish again. Now with the help of BLFS I am setting up my environment and somewhere I incidentally read, that not every variable is inherited by a child Bash shell.

I have searched stackexchange and other website for the difference. It is said that environment variable is inherited in child processes but shell variables are not. However the following test shows shell variables are seen in child process just as environment variables. Any suggestion please?

It is said that environment variables are inherited in child processes but shell variables are not. However the following test shows shell variables are seen in child process just as environment variables.

I need to set an environment variable called "64bit" (i.e. with a leading digit) in bash. However, bash variable names disallow a variable with a leading digit. I know a way to set it when invoking bash:

env 64bit=1 /usr/bin/bash

However, I'm looking for a way to change it in the currently running shell i.e. not by starting a new shell.

From tcsh, if I try:

exec /home/path/to/my/zsh

it works (I enter a Zsh shell)

but if I try

exec -c /home/path/to/my/zsh

I get:

-c Command not found

How do I switch to my Zsh shell and start it from a "blank slate"? (i.e. with no environment variables carried over from tcsh ).

Just to clarify: I know we can set environment variables with export command like export JAVA_HOME=/usr/lib/jvm/..

For environment variables, we need to use '$' sign in starting and we can not explore the path further using 'tab' key.

I have OSX 10.8.2 with ZSH as my shell and iTerm as a terminal (don't know if the last thing is relevant).

From the lfs doc:

The exec env -i.../bin/bash command in the .bash_profile replaces the running shell with a new one with a completely empty environment, except for the HOME, TERM, and PS1 variables. This ensures that no unwanted and potentially hazardous environment variables from the host system leak into the build environment.

I encountered a strange issue this morning. My $PATH environment variable is screwed up by a command

export PATH=./releases/bin:$PATH

It is totally okay to run this under a existing shell, the issue is I put it in the shell startup shell script .profile.