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Old 12-14-2008, 12:12 AM   #1
swamprat
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Registered: Sep 2005
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Deleting a Path from $PATH


Some one was good enough to help me out with setting a new path in the $PATH variable:

"export PATH=/some/new/path/bin:$PATH"

Now I would like to delete a path from this variable ... how would this be done?

thanks

Last edited by swamprat; 12-14-2008 at 12:13 AM.
 
Old 12-14-2008, 12:35 AM   #2
penguiniator
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This is a stickier problem than I thought it would be. I found a snippet on LJ that seems to answer your question.

http://www.linuxjournal.com/content/...th-variable-0:
Quote:
If you need to remove a path from the PATH variable before your script runs add this to the beginning of the script:

PATH=$(echo $PATH | sed -e 's;:\?/home/user/bin;;' -e 's;/home/user/bin:\?;;')

If you need, you can re-add it at the front of the list with:

PATH=/home/user/bin:$PATH

Or you can re-add it at the end of the list with:

PATH=$PATH:/home/user/bin
I didn't test this, so be warned.
 
Old 12-14-2008, 02:10 AM   #3
blackhole54
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I wasn't aware that sed could use a question mark to mean "zero or one instances of preceding character" (appears to be an error in my copy of Linux in a Nutshell), so I was hoping the Linux Journal reference would explain the logic. It didn't. (BTW, here is the link w/o the colon tagged on the end. ) But when I tried the command out it didn't seem to work. And playing around with removing the backslashes (which I thought were wrong) only got me completely confused. So if somebody can give me a coherent explanation of the use of those questions marks and (possibly) backslashes, I would appreciate it. In the meantime, here is a version I understand and I am pretty sure it works:

Code:
PATH=$(echo :$PATH | sed "s@:/path/to/remove@@; s@^:@@")
Explanation: I add a colon before $PATH so that first path element is not special. The sed command deletes the undesired path along with its preceding colon and then deletes the (remaining) initial colon for the string. The same idea could be applied with a colon added to the end instead, with appropriate changes to the sed command.

EDIT:

Upon further reflection I realized that if the path element to delete matches part of another path element, the above statement could result in doing something other than what was intended. (I believe the statement from the LJ article also suffers from this.) This problem can be avoided by bracketing the element to delete with colons on both sides:

Code:
PATH=$(echo :$PATH: | sed "s@:/path/to/remove:@:@; s@^:@@; s@:$@@")

Last edited by blackhole54; 12-15-2008 at 11:38 PM.
 
Old 12-14-2008, 02:49 AM   #4
John VV
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the easiest way might be to remove the path from ~/.bash_profile if it is in there
or from/etc/bash_profile
 
  


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