Is there a bash shortcut for traversing similar directory structures?

Question

The Korn shell used to have a very useful option to cd for traversing similar directory structures e.g. given the following directorys

• /home/sweet/dev/projects/trunk/projecta/app/models
• /home/andy/dev/projects/trunk/projecta/app/models

Then if you were in the /home/sweet.... directory then you could change to the equivalent directory in andy's structure by typing

cd sweet andy

So if ksh saw 2 arguments then it would scan the current directory path for the first value, replace it with the second and cd there. Is anyone aware of similar functionality in bash.

EDIT 1

Following on from Michal's excellent answer I have now created the following bash function called scd (For Sideways cd)

function scd {
  cd "${PWD/$1/$2}"
}

EDIT 2

Thanks to @digitalross I can now reproduce the ksh functionality exactly with the code from below (With the addition of a pwd to tell you where you have changed to)

cd () {
  if [ "x$2" != x ]; then
    builtin cd ${PWD/$1/$2}
    pwd
  else
    builtin cd "$@"
  fi
}

Answer 1

No, but...

Michał Górny's substitution expression works nicely. To redefine the built-in cd command, do this:

cd () {
  if [ "x$2" != x ]; then
    builtin cd ${PWD/$1/$2}
  else
    builtin cd "$@"
  fi
}

Answer 2

cd "${PWD/sweet/andy}"

Answer 3

Other solutions offered so far suffer from one or more of the following problems:

• Archaic forms of tests - as pointed out by Michał Górny
• Incomplete protection from directory names containing white space
• Failure to handle directory structures which have the same name used more than once or with substrings that match: /canis/lupus/lupus/ or /nicknames/Robert/Rob/

This version handles all the issues listed above.

cd () 
{ 
    local pwd="${PWD}/"; # we need a slash at the end so we can check for it, too
    if [[ "$1" == "-e" ]]
    then
        shift
        # start from the end
        [[ "$2" ]] && builtin cd "${pwd%/$1/*}/${2:-$1}/${pwd##*/$1/}" || builtin cd "$@"
    else
        # start from the beginning
        [[ "$2" ]] &&  builtin cd "${pwd/\/$1\///$2/}" || builtin cd "$@"
    fi
}

Issuing any of the other versions, which I'll call cdX, from a directory such as this one:

    /canis/lupus/lupus/specimen $ cdX lupus familiaris
    bash: cd: /canis/familiaris/lupus/specimen: No such file or directory

fails if the second instance of "lupus" is the one intended. In order to accommodate this, you can use the "-e" option to start from the end of the directory structure.

    /canis/lupus/lupus/specimen $ cd -e lupus familiaris
    /canis/lupus/familiaris/specimen $

Or issuing one of them from this one:

    /nicknames/Robert/Rob $ cdX Rob Bob
    bash: cd: /nicknames/Bobert/Rob: No such file or directory

would substitute part of a string unintentionally. My function handles this by including the slashes in the match.

    /nicknames/Robert/Rob $ cd Rob Bob
    /nicknames/Robert/Bob $

You can also designate a directory unambiguously like this:

    /fish/fish/fins $ cd fish/fins robot/fins
    /fish/robot/fins $

By the way, I used the control operators && and || in my function instead of if...then...else...fi just for the sake of variety.