compact-pwd patch for bash

[Zsban Ambrus]

        compact-pwd patch for bash

INTRODUCTION

It is very convenient to display the working directory in the shell prompt.
This, however, can get very annoying as well, when you cd to a directory
with long name.  The prompt gets inconveniently long in this case.

I have written a remedy for this problem.  After rebuilding bash with my
patch, if you replace \w with \S in the PS1 parameter, the working directory
will be displayed abbreviated.  Only the first letter of each directory
component is displayed, and maybe some other letters to distinguish the
directory from other files or directories.  Let's see some examples.
Propose I set PS1='\S\$ '.  If I cd to the directory

/usr/lib/perl5/site_perl/5.005/i586-linux/auto/QRadioButton

the prompt is:

/u/li/pe/s/5/i/aut/QRad$

This means that if filename completion is enabled, you can cd to this
directory by typing:

cd /u<TAB>/l<TAB>i<TAB>/p<TAB>e<TAB>/s<TAB>/5<TAB>/i<TAB>/a<TAB>u<TAB>t<TAB>/
Q<TAB>R<TAB>a<TAB>d<TAB><ENTER>

You can still display the full name of the directory with the pwd command.

There are some special exceptions: the /usr/local and the /usr/share
directories are printed as /u/l and /u/s respectivly, instead of /u/lo and
/u/sh.  Also a tilde (~) is used instead of $HOME, as bash does it already.
For example

/usr/local/Wolfram/Mathematica/5.0/AddOns/JLink/Documentation/JavaDoc/com

is displayed as:

/u/l/W/M/5/A/J/D/J/cm$

And /usr/share/man/man1 is displayed as /u/s/ma/m1.

If you do not have read access for the parent of a directory, the directory
will be spelled out fully.


DETAILS

The patch is written for bash version 2.05b.  It may or may not work for
other versions.  It may also be buggy.

I only tested the patch on i686 Linux, it may not be portable for other
systems.  This is true especially for the readdir call.

Apply the patch with the -p option.  
Do not forget to rerun configure if you apply the patch to an already
configured bash, as the patch adds new #include dependencies.
Here is an example to build bash with
the patch. 

$ tar -xzvf bash-2.05b.tar.gz
$ <compact-pwd/compact-pwd.patch patch -p0
$ cd bash-2.05b
$ ./configure
$ make
$ make install

I include the patch in the message uuencoded.

This patch does not come with any warranty at all.  I am not sure if it
works in all cases or not.  Use at your own risk.


AUTHOR

Zsban Ambrus  <ambrus@math.bme.hu>
2004 Jan 17 


PATCH

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end