linux - Is it possible to have environment variables in the path of the working directory : PS1?

05
2013-12

mthpvg

I am on Lubuntu and I am using bash. My PS1 (in .bashrc) is :

PS1="\w> "

I like it because I need to paste the working directory all the time. The problem is that the path is always very long and since I use terminator I only have half of my screen's width available to display it... it is ugly and annoying. My command prompt looks like that :

/this/is/a/very/long/path/that/i/want/to/make/shorter >

I'd like to set in my environment variables :

$tiavl=/this/is/a/very/long

And then I'll get :

$tiavl/path/that/i/want/to/make/shorter >

The goal is to have something shorter in the command prompt but I still want to be able to copy paste it and do :

cd $tiavl/path/that/i/want/to/make/shorter

It is a bit like with $HOME :

~/path/that/i/want/to/make/shorter  >

I know where I am and I can copy paste the ~.

Thanks.

Answers

Mat

You can do this with a little helper function, as below (use /home as an example prefix path):

~ > pwd
/home/me
~ > tiavl=/home
~ > prompt_path () { echo ${1/#$tiavl/\$tiavl}; }
~ > export PS1="\$(prompt_path \w) > "
$tiavl/me >

This uses a simple string manipulation function (see here for lots of examples) in the function to replace the initial part of the path with a literal $tiavl if it matches.

Here's a demo of how to update that function for several paths.

#! /bin/sh

path1=/home
path2=/usr
path3=/var

prompt_path() {
    local path
    path="${1/#$path1/\$path1}"
    path="${path/#$path2/\$path2}"
    path="${path/#$path3/\$path3}"
    echo "$path"
}

prompt_path $HOME
prompt_path /usr/local
prompt_path /var/tmp

samir

If you copy paste in the terminal, you can just use $PWD environment variable which will always show you the working directory.

echo $PWD

shows the working directory.

mthpvg

So basically you make a bash script :

prompt_path

which contains :

#! /bin/sh
path="${1/#$path1/\$path1}"
path="${path/#$path2/\$path2}"
path="${path/#$path3/\$path3}"
echo "$path"

You place it in a folder like :

~/.local/bin

You give x right to your script :

chmod u+x prompt_path

In your ~/.bashrc :

1 - you change PS1 to :

PS1="\$(prompt_path \w) > "

2 - you add those lines :

export path1=/home
export path2=/usr
export path3=/var

3 - you indicate so that you can call your script from anywhere:

export PATH=~/.local/bin:$PATH

Finally you source your .bashrc :

. ~/.bashrc

Related Answers

Peter

Your shell is trying to set the XTerm's (or other console) title/header. There are a number of ways this might be being done.

First make sure the PS1 is really what you think it is

echo $PS1 | less -E

That will tell you if there are control characters in the prompt, less will make them look funny. Assuming your prompt is exactly as you say, then it is probably the PROMPT_COMMAND environment variable. You can look at that the same way...

echo $PROMPT_COMMAND | less -E

If the prompt command is the problem, then you can just unset it. In either case, these variables are being set up somewhere, and should not be set to update the XTerm header, if you're not in an XTerm!

You can look in the "standard" bashrc (/etc/bashrc). You should see code that checks for an iteractive shell (is PS1 set), and then checks for xterm (looking at $TERM variable), and does something different there than for other terminal types.

I suspect somewhere in the bash initialization is a hard-coded setup, which should only be done on xterm-compatible console programs. Read man bash to find a total list of files you can look for and through.

If all of the above fails, try

printenv | less

And see if you can find something suspicious in there, and then track down where it is being set. Post it here if you can't work it out.

SG1

I came across exact same problem and it is due to PROMPT_COMMAND. I like the xterm title. So I added following line in ~/.emacs_bash

export PROMPT_COMMAND=""

luapyad

It may be something to do with the terminal type of the emacs shell vs your regular shell. Check what the TERM environment variable is set to in both shells. If they are different then you should be able to change the emacs shell terminal type or use a different PS1 definition for the emacs terminal type in .bashrc.

You could also try M-x ansi-term (and ansi-color-for-comint-mode-on if you have colour prompts).

This was answered very well on the stackoverflow site. by Daniel Poe.

Here's his answer.

You can use AnsiTerm which does support colors or you can enable AnsiColor for the normal shell:

(autoload 'ansi-color-for-comint-mode-on "ansi-color" nil t)
(add-hook 'shell-mode-hook 'ansi-color-for-comint-mode-on)

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linux - Is it possible to have environment variables in the path of the working directory : PS1?