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Quickly changing between similar directories in BASH @ 08 Feb 2012

I recently discovered a nifty trick in the cd builtin provided by ZSH: the ability to change from the current directory to another whose path is generated via simple (and, for better or worse, non-global) search-and-replace:

% pwd
/top/left/bottom
% ls /top/*
/top/left:
bottom

/top/right:
bottom
% cd left right
/top/right/bottom
% pwd
/top/right/bottom

Unfortunately, users of BASH don't get this nicety; however, by adding a (somewhat) simple function to your shell config (~/.bashrc or perhaps ~/.bash_profile), you can emulate this behavior:

cd () {
    if [ $# -eq 1 ]; then
        builtin cd ${1}
    elif [ $# -gt 2 ]; then
        echo -e "usage: cd path" >&2
        echo -e "       cd to_replace replace_with" >&2
        return 1
    else
        local new_pwd=$(echo ${PWD} | sed "s/${1}/${2}/")
        builtin cd ${new_pwd} && echo ${new_pwd}
    fi
}

Note that this isn't perfect. For example, it will not work with values of to_replace or replace_with that contain forward slashes (or anything else that will mess with the sed command). There are certainly more involved methods that would avoid the limitations seen here.

Update (18 Feb 2011)

Josh Berry points out that this can be done using BASH's built-in string manipulation in place of sed. The relevant line in the above function can be replaced with the following:

local new_pwd=${PWD/${1}/${2}}