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Old 11-14-2005, 01:05 PM   #1
suneel
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Registered: Nov 2005
Location: Hyderabad
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how to unset environment variable in bash


Hi,
I am using bash(Fedora 3). I have set an enviroment variable using:
export temp='Helo world'
How do I remove temp from enviroment?
I guess this can be done in csh using unsetenv.
One more question: Whats the difference between the output of a set and export with out options. (Both of them print all the environment variables. export just prints all the variables prefixed with 'declare -x'. What is it meant for?)
 
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Old 11-14-2005, 02:49 PM   #2
bosewicht
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env --unset=helo world

To remove variable helo world.

 
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Old 11-14-2005, 10:06 PM   #3
foo_bar_foo
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unset temp
 
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Old 11-15-2005, 01:14 PM   #4
suneel
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Hi bosewicht,
I tried your suggestion ie env --unset=temp. But it just printed all the environment variables without unsetting temp.

Hi foo_bar_foo,
thanks for the reply. It works
 
Old 11-30-2005, 01:22 PM   #5
shevegen
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How do I delete all Variables?
 
Old 11-30-2005, 09:21 PM   #6
arrenlex
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You really don't want to. If you unset your PATH, for example, you won't be able to run any applications and you might have a ton of trouble putting it back.

I suggest running the 'env' command to list all variables defined on your system and unset only the ones you know you don't need or want.

With Linux, it's generally a very bad idea to delete something when you don't know what it is\does.
 
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Old 03-09-2009, 12:30 PM   #7
sharky
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Quote:
Originally Posted by arrenlex View Post
You really don't want to. If you unset your PATH, for example, you won't be able to run any applications and you might have a ton of trouble putting it back.

I suggest running the 'env' command to list all variables defined on your system and unset only the ones you know you don't need or want.

With Linux, it's generally a very bad idea to delete something when you don't know what it is\does.
Sometimes I do want to unset everything. I build startup scripts for endusers running ic design tools. To try and have all tools run in identical environments start all my scripts with the following:

Code:
#!/bin/tcsh -f

# get USER, HOME and DISPLAY and then completely clear environment
set U = $USER
set H = $HOME
set D = $DISPLAY
unsetenv *

# set USER, HOME and DISPLAY and set minimal path.
setenv USER $U
setenv HOME $H
setenv DISPLAY $D

# initial path
set path = (/bin /usr/bin /usr/local/bin /usr/bin/X11 /usr/contrib/bin \
/usr/contrib/bin/X11)
I grab USER, HOME and DISPLAY and flush the rest. I then set a minimal path. I would like to know how to do something similar in bash.
 
Old 09-14-2009, 11:17 AM   #8
linuxLuser
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Unset ALL environment variables in BASH (not a good idea!):

Code:
$ unset `env | awk -F= '/^\w/ {print $1}' | xargs`
$ env
bash: env: No such file or directory
$ ls
bash: ls: No such file or directory
Enjoy.
 
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