Adding to path so that file is available everywhere - bash

Question

I am trying to add several directories to my path so that the files in that directory and it's subdirectories are available for me from the command prompt across sessions.

export PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/home/username/OpenFOAM/OpenFOAM-2.1.0/etc/bashrc:/usr/share/texmf-texlive/tex/latex:/etc/crontab:/home/username/Research/Dissertation/wigner/ic/L=lambda:/home/username/Research/Dissertation/wigner/ic/L=2lambda:/home/username/Research/Dissertation/wigner/ic/L=3lambda:/home/username/Research/Dissertation/wigner/ic

Appending the follwing

 /home/username/Research/Dissertation/wigner/ic/L=lambda:/home/username/Research/Dissertation/wigner/ic/L=2lambda:/home/username/Research/Dissertation/wigner/ic/L=3lambda:/home/username/Research/Dissertation/wigner/ic

to the export PATH line of my .bashrc and sourcing it didn't help. What am I doing wrong? When I try to access files from say /home/username/Research/Dissertation/wigner/ic, I can't.

I've read a few posts here but they didn't really help at all. Am I missing colons, semicolons, dollar symbols?

Answer 1

It sounds like you might be misunderstanding the purpose of $PATH. $PATH merely tells Bash where to look for executable files and scripts. For example, this command:

foo bar.txt

will (usually) search $PATH for an executable file named foo, and these commands:

bash foo.sh
. foo.sh

will (usually) search $PATH for foo.sh unless there's a foo.sh in the current directory; but these commands:

cat foo.txt
vi foo.txt
less foo.txt

will not search $PATH for foo.txt.

Furthermore, you write of "the files in that directory and it's subdirectories", but $PATH is not useful for subdirectories. Bash will never search $PATH if the executable-name contains /. For example, this command:

foo/bar baz.txt

will run ./foo/bar, and will not search $PATH for a directory named foo.

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Edited to add: So, what you can do instead . . .

Ultimately, you need to include directory information in your montage command:

cd /home/username/Research/Dissertation/wigner/ic
montage -geometry +4+4 L=3lambda/three.jpg L=2lambda/two.png output.jpg

If the directory information is too much of a pain to type every time, you can set up your own variable in .bashrc, and then use it explicitly. For example, .bashrc might have:

export IC=/home/username/Research/Dissertation/wigner/ic
export ICL=$IC/L=lambda
export ICL2=$IC/L=lambda2
export ICL3=$IC/L=lambda3

and then you could write:

montage -geometry +4+4 $ICL3/three.jpg $ICL2/two.png output.jpg

If you don't even want to remember what subdirectory a given file is in, you can use a fileglob:

export IC=/home/username/Research/Dissertation/wigner/ic
export ICLs=$IC/L=lambda*

and write:

montage -geometry +4+4 $ICLs/three.jpg $ICLs/two.png output.jpg

letting the shell find it for you. (But of course, this will only work properly if there are no name-conflicts between files in different subdirectores.)

Answer 2

You could define a few variables in your .bashrc:

H="/home/username/Research/Dissertation/wigner/ic"    
oneLam="$H/L=lambda"
twoLam="$H/L=2lambda"
threeLam="$H/L=3lambda"

so that referring to files can be done from anywhere like so:

user@box:/some/horrendously/deep/path/$ vi $twoLam/some_file.txt