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Comment by kazinator | Hacker News Reader

~-2 is shorter than messing with the dirs command but it does not improve over $c2. It does not rescue the whole directory stack misfeature which has no reason for existing as built-in C code inside Bash, with dedicated expansion syntax. It interferes with existing syntax, too; according to POSIX, that refers to the home directory of a user named -2.

We can "export c1" and the others to make them visible to child processes. That makes it possible to launch a subshell in which the parent shell's directory log is readily available.

Things that can be very effectively and ergonomically achieved with a bit of scripting in the user's environment should never be built into the command interpreter. That just adds to the executable size, documentation, and maintenance.

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Personally, I'd find the completion output from `~-<Tab>` a worthy improvement, although admittedly with zsh you can configure completion to display both name and value for `$c<Tab>` too I guess(can't recall if that is possible with bash).

User names should not begin with a hyphen¹, so it shouldn't interfere with home directory references.

The child process point is an interesting one, I feel like you could workaround it by using a chpwd hook to export $dirstack and set it at startup(or a precmd function and $DIRSTACK if using bash). Something like `export DIRSTACK=${(pj#:#)dirstack}` in the hook and `dirstack=(${(ps#:#)DIRSTACK})` in the startup file. I'll concede this point though, as while a fun thought experiment the end result would be ghastly ;)

¹ https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1...

I'm noticing that in Bash, when I complete on ~-1 without a trailing slash, nothing happens. When I use $c1 and hit tab, it adds the slash for me! So in that situation, $c1 saves a keystroke. Well, not a keystroke per se, but having to use a different character rather than repeated Tab.

Also, I can shorten these variables to one letter, like $p, $q, ...

Bash has an option so that tab completion will expand out the directory.

  shopt -s direxpand

this is useful because variables like $c1 or syntax like ~-1 entered into the history is not useful for recall.

I know about M-x C-e to expand everything, but that is far too clumsy compared to just the tab completion doing it.

Here is something: the direxpand option is not working for ~-n/[Tab] completions. Only for variable names!

My description above wasn't great. I meant completion would be an improvement in the sense that under zsh `~-<Tab>` can show not only the possible completion options, but also the value they expand to. For example, mine is set to display in the manner of a colorful version of the text below:

    $ cd ~-
    0 -- ~
    1 -- ~/Downloads
    2 -- ~/Desktop

The handling of tilde expansion under bash is a readline option, so users would configure it in their inputrc. It is pretty useful in general, because then it is also available to tools like imv¹ beyond just bash. Unfortunately, as it is handled separately from word completion you'd need to change the completion function to make it match the mark-directories behaviour you like.

If I wanted the text expanded for history use I'd probably expand it before writing using a zshaddhistory hook, but I don't think there is an equivalent in bash so changing the line buffer probably is the best option.

¹ https://www.nongnu.org/renameutils/

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