last three level of `pwd` 1

[lmm8294]

I need to modify the .profile of an account, and I have this line in the .profile:
PS1=`hostname`':$LOGNAME:$PWD>'

But my boss want me to get only the last 3 levels of the subdirectory if `pwd` returns a long path. For example, if `pwd` returns /appl/oracle/instance001/d01/oracle/001appl/admin,

then he want only oracle/001appl/admin displayed. Could anybody help me? I have tried to use 'cut -d/ -f ...', but it does not work for me because I don't know how to count the occurance of '/' from `pwd`. I posted this question on the UNIX script forum, and Tanda suggests me to ask help from this forum. I appreciate it if anybody can help me with this problem.


Thanks in advance.

 

[JimJx]

I know that there must be a much more elegant way of doing this, but this should help.......

In the code, $string needs to be equal to the path you are trying to work with.....

$pos = length $string;
$count = 3;

while ($count>0) {
$char = substr $string, $pos, 1;
if ($char eq '/') {
	$count--
	}
	$pos--
	}
	$new = substr $string, ($pos + 1);

With this I am assuming that all of your paths will contain at least 3 '/' characters. If not, you will need to add a if statement to check $pos to find out when it reaches the beginning of the line and return whatever result you have up to that point....

Based on your example of
/appl/oracle/instance001/d01/oracle/001appl/admin
this will return
/oracle/001appl/admin

if you want to kill the first / to get
oracle/001appl/admin

change
$new = substr $string, ($pos + 1);
to
$new = substr $string, ($pos + 2);

As I said in the beginning of this, there has gotta be a better way, but this is what I came up with off the top of my head.

Let me know how it works
Jim

 

[toolkit]

Another way of doing this is:

$path = "/some/path/to/a/directory";
@toks = split </>, $path;
@toks = splice( @toks, -3, 3 );
print join(&quot;/&quot;, @toks), &quot;\n&quot;;

See man perlfunc for an explanation of the splice function.

Cheers, NEIL

 

[JimJx]

Cool, I knew there had to be a better way

 

[tsdragon]

That's a pretty elegant solution!
Tracy Dryden
tracy@bydisn.com

http://www.bydisn.com

Meddle not in the affairs of dragons,
For you are crunchy, and good with mustard.

 

[lmm8294]

Thank you very much for Jim and ToolKit. It is really nice to get responses so quickly. All of your responses are really helpfule. I will try both ways and let you know if it works.


Thank you very much again.

 

[lmm8294]

I have tried the second one, the script it self works very well. Thank you very much.
But the problem is, it works only when I log on or su - to that user. The perl file /home/apoap003/test contains the code provided by ToolKit, and in the /home/apoap003/.profile I have PS1 defined as below:

PS1=`hostname`':$LOGNAME:'`/home/apoap003/test`'>'

It works if I log on and the .profile was sourced the first time, but does not work if I cd to other directories. But if I manually source the .profile after I cd to other directories like $ORACLE_HOME, it works.

Any suggestion?

Thank you very much again.

 

[toolkit]

Hmm..

Perhaps you could define a function to do this for you? For example, in bash, I think something like this could work:

function cd() {
    builtin cd $1
    $cropped=$(/path/to/perl/cropper $1)
    PS1="${cropped}$ "
}

I myself use a cd function to define one letter aliases for my favourite directories, eg:

function cd() {
    case $1 in
        a) builtin cd /LOCAL/awesome;;
        b) builtin cd /tmp/bogus;;
        e) builtin cd /tmp/EXCELLENT;;
    esac
}

I'm not in front of my UNIX box at the moment, so I can't test the code above. Tell me if you have any problems ;-)

Cheers, NEIL

 

[toolkit]

And obviously my case statement would need:

   *) cd $1;;
esac

Happy coding. Neil s-)

 

[lmm8294]

It works fine. Thanks a lot. Really appreciate it.

 

[andimue]

If you use the bash-shell take a look at :

http://www.shelluser.net/~giles/bashprompt/prompts/index.html

they got really cute prompts.

I use to display the full path in the prompt and also change to x-window-title to username&machineath

part of my .bashrc - file:
PROMPT_COMMAND='echo -ne "\033]0;`/usr/ucb/whoami`@${HOSTNAME}: ${PWD}\007"'
PS1="\u@\h:\w > "

if u wanna see only the last sub-directory use :
# PS1="[\u@\h \W]\\$ "