qswitch - quickly switch directory from bash prompt

Purpose

I use the command line (shell) for almost everything. However, sometimes I found myself spending more time cd'ing from directory to directory than actually doing something useful ;-)

To avoid this, I wrote a small script that allows changing directories using "aliases" defined in a separate file. These aliases are searched for (partial) matches, and a cd to this directory is executed. The script allows for TAB completion of these aliases (and directories, if new ones are specified) and thus is very fast to use.

Usage

Change to a certain directory

Type qsw followed by an alias or part of an alias. TAB completion is provided. Note that qsw will cd to the directory with the best match based on some fuzzy matching algorithm.

qsw alias

Add, remove, and modify aliases

qsw --add <alias> <directory> # e.g. qsw --add myshortcut .

qsw --remove alias

qsw --modify alias directory

Aliases can be added/removed/modified as indicated above. Tab completion works for the alias (e.g. remove and modify) and the directory (add, 2nd argument).

The use of an "--option" may be unorthodox for "subcommands" with arguments but has the advantage that it does not interfere with TAB completion of the aliases.

List all aliases

qsw --list

Edit the alias definitions

For major cleanups, it is possible to edit the alias file, optionally specifying the editor to be used. By default, the editor specified by the environment variable SELECTED_EDITOR is used, or ~/.selected_editor scanned for such a definition. Alternatively, some editors can be specified on the command line. I exclusively use nano, emacs, and sometimes kate, but the script is simple to adapt if you have other preferences. Being able to chose the editor is important: For example, nano will fail terribly within an emacs eshell.

qsw --edit

qsw --nano

qsw --kate

qsw --emacs

The alias definition file has the following format

alias1, /full/path/directory1
alias2, /full/path/directory2

Installation

I have two versions of the script. The old one is written in Perl and I used it with bash. The new one is written in Python and I use it with fish, which recently has become my default shell because it is so much more intuitive, not least for programming.

The new Python script should also work with bash, but I have not tried it.

Perl script (which I used with bash)

Commands run from bash cannot change the current directory of the calling process. Therefore, the script is executed in two stages. First, a bash function (here named qsw, for "Quick SWitch", which is very fast to type) executes the perl script _qswitch.pl. The output of the perl script is captured and used to cd into the selected directory.

Copy the qswitch.pl file to a directory that is writable (the alias file will be placed in the same directory). Then, create a symlink from /usr/local/bin/_qswitch to qswitch.pl.

In my .bashrc file, I have:

qsw() {
    CD=$( _qswitch $@)
    cd "$CD"
}

_qsw_complete() {qsw 
    COMPREPLY=($(COMP_CWORD=$COMP_CWORD perl /usr/local/bin/_qswitch ${COMP_WORDS[@]:0} ))
}

complete -F _qsw_complete qsw

Python script (which I use with fish)

With my switch to fish, I translated my old Perl script to Python.

First, two environment variables with the program to execute and the location of the shortcut text file have to be set. I do this in a script in ~/.config/fish/conf.d.

set -gx QSW_DB /path/to/your/shortcuts.txt
set -gx QSW_EXE /path/to/qswitch.py

Then, a function named qsw (or whatever) needs to be defined. I do this in ~/.config/functions.

function qsw
    set -l DIR (command  $QSW_EXE $argv)
    if test $status = 0
        cd $DIR
    end
end

TAB completion is added in ~/.config/fish/completions/qsw.fish:

## completions of shortcuts
function __qsw_complete_shortcuts
    cat $QSW_DB | cut -d"," -f1
end

## qsw --add ALIAS PATH
complete -f -c qsw -l add --no-files
## qsw --edit [--kate|--emacs|--nano]
complete -f -c qsw -l edit --no-files
## qsw --list
complete -f -c qsw -l list --no-files
## qsw --modify ALIAS PATH
complete -f -c qsw -l modify -ra "(__qsw_complete_shortcuts)"
## qsw --remove ALIAS
complete -f -c qsw -l remove -ra "(__qsw_complete_shortcuts)"
## qsw ALIAS
complete -f -c qsw -a "(__qsw_complete_shortcuts)"