Adding to the PATH but not if already in $PATH

I want to prepend a directory to my PATH in my $HOME/.bashrc and export the
result. But I only want it to happen once: iow, if a directory I want
prepended is already in the PATH, do not prepend it again.

Something like:

if "/home/dw/bin" not in $PATH ; then
PATH=/home/dw:$PATH
export PATH
fi

The questions are: Is this the way one guards against multiple additions in
subshells? Is there a way to check for a substring?

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Re: Adding to the PATH but not if already in $PATH

Dog Walker wrote:
> I want to prepend a directory to my PATH in my $HOME/.bashrc and export the
> result. But I only want it to happen once: iow, if a directory I want
> prepended is already in the PATH, do not prepend it again.
>
> Something like:
>
> if "/home/dw/bin" not in $PATH ; then
> PATH=/home/dw:$PATH
> export PATH
> fi
>
> The questions are: Is this the way one guards against multiple additions in
> subshells? Is there a way to check for a substring?
Hi, DW:

-----
#!/bin/sh
#
# file /usr/local/bin/phwb.sh
#
# This prepends "/home/dw/bin/" to $PATH
PATH=/home/dw/bin:$PATH
export PATH
#end
-----

>touch /home/dw/bin/phwb.sh
>chmod +x /home/dw/bin/phwb.sh
> phwb.sh

If there is already a path to /home/dw/bin,
then the 0 byte file /home/bin/dw/phwb is executed.
else: /usr/local/bin/phwb.sh is executed.


HTH, Chuck


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