Because we now count the extension including the ".", we print an
empty entry.
This makes e.g.
```fish
set -l base (path change-extension '' $somefile)
set -l ext (path extension $somefile)
echo $base$ext
```
reconstruct the filename, and makes it easier to deal with files with
no extension.
This means "../" components are cancelled out even after non-existent
paths or files.
(the alternative is to error out, but being able to say `path resolve
/path/to/file/../../` over `path resolve (path dirname
/path/to/file)/../../` seems worth it?)
Yeah, the macOS tests fail because it's started in /private/var... with a
$PWD of /var.... So resolve canonicalizes the path, which makes it no
longer match $PWD.
Simply use pwd -P
This just goes back until it finds an existent path, resolves that,
and adds the normalized rest on top.
So if you try
/bin/foo/bar////../baz
and /bin exists as a symlink to /usr/bin, it would resolve that, and
normalize the rest, giving
/usr/bin/foo/baz
(note: We might want to add this to realpath as well?)
This includes the "." in what `path extension` prints.
This allows distinguishing between an empty extension (just `.`) and a
non-existent extension (no `.` at all).
This adds a "path" builtin that can handle paths.
Implemented so far:
- "path filter PATHS", filters paths according to existence and optionally type and permissions
- "path base" and "path dir", run basename and dirname, respectively
- "path extension PATHS", prints the extension, if any
- "path strip-extension", prints the path without the extension
- "path normalize PATHS", normalizes paths - removing "/./" components
- and such.
- "path real", does realpath - i.e. normalizing *and* link resolution.
Some of these - base, dir, {strip-,}extension and normalize operate on the paths only as strings, so they handle nonexistent paths. filter and real ignore any nonexistent paths.
All output is split explicitly, so paths with newlines in them are
handled correctly. Alternatively, all subcommands have a "--null-input"/"-z" and "--null-output"/"-Z" option to handle null-terminated input and create null-terminated output. So
find . -print0 | path base -z
prints the basename of all files in the current directory,
recursively.
With "-Z" it also prints it null-separated.
(if stdout is going to a command substitution, we probably want to
skip this)
All subcommands also have a "-q"/"--quiet" flag that tells them to skip output. They return true "when something happened". For match/filter that's when a file passed, for "base"/"dir"/"extension"/"strip-extension" that's when something about the path *changed*.
Filtering
---------
`filter` supports all the file*types* `test` has - "dir", "file", "link", "block"..., as well as the permissions - "read", "write", "exec" and things like "suid".
It is missing the tty check and the check for the file being non-empty. The former is best done via `isatty`, the latter I don't think I've ever seen used.
There currently is no way to only get "real" files, i.e. ignore links pointing to files.
Examples
--------
> path real /bin///sh
/usr/bin/bash
> path extension foo.mp4
mp4
> path extension ~/.config
(nothing, because ".config" isn't an extension.)
