A tale of two path separators

A tale of two path separators(alexwlchan.net)

36 points by dbaupp 4 days ago | 10 comments

pedromlsreis 26 minutes ago |

I'm curious how much of this behaviour is still intentional design vs. just inertia. Are the modern filesystems still constrained by these older choices, or is it mostly for compatibility?

p_l 25 seconds ago | |

Filesystems usually do not see path separators at all, it's something handled at VFS level

VorpalWay 3 hours ago |

Old Macs (which I grew up with) had even more baroque path handling than mentioned in the blog post:

Double colon (::) meant the same as .. on Unix/DOS, that is "go up one level". So you have to be careful when concatenating paths to not get double separators.

Paths starting with : were relative. If a path didn't start with the separator, the first component was the volume name (disk partition). Again, quite unlike Unix.

Also, remember it was common to have spaces in names on Mac, even the default harddrive on Macs was named "Macintosh HD". So an absolute path like "Macintosh HD:Programs:MacWrite" would have been common. (I grew up with Macs in Swedish, so I'm back translating the names here, could be that the names were slightly different in English.)

BoingBoomTschak 1 hour ago | |

Fun things is that I encountered that for the first time when using Clozure CL (https://ccl.clozure.com/) which quotes colons when converting paths to string even on Linux:

  $ cat <<'EOF' >x.lisp
  heredoc> (require :uiop)
  heredoc> (let ((p (make-pathname :name "foo:bar")))
  heredoc>   (format t "~@{~A~%~}" (namestring p) (uiop:native-namestring p)))
  heredoc> EOF
  $ ccl -b -Q -l x.lisp </dev/null
  foo\:bar
  foo:bar
  $ sbcl --script x.lisp
  foo:bar
  foo:bar

fragmede 2 hours ago | |

Current macOS Finder let's you name files with a slash in them, rendered as a : in the terminal.

VorpalWay 2 hours ago | | |

Isn't that just what the original article that we all commented on described? I don't understand what you are trying to add to the conversation here.

microtonal 2 hours ago | | |

I think that the slash might be the rendering though? If you

    $ touch "foo:bar"

In the Terminal, then Finder renders it as foo/bar.

So who is lying, how is it stored in the directory entry in APFS itself?

windowliker 3 hours ago |

It took me a long time to understand why colon wasn't a valid character for file names on Mac and I still find the colon separator to be the least visible these days. Finder can display paths with the forward slash separator (defaults write com.apple.finder _FXShowPosixPathInTitle -bool YES), and yet forward slash may be used in a file name created through Finder as noted in the post, while colon cannot (which is not addressed), but creating a file in the terminal named with a colon is possible and the shell will escape it correctly in use. This file then shows up with a slash in place of the colon when viewed in Finder, and conversely the file with a slash in the name shows up in Terminal with a colon!

breppp 1 hour ago |

I was expecting the story of the magical ¥ path separator

bebe83939 1 hour ago |

Now imagine operating system, that has no directories (and no path separators) or no filesystem at all.

rswail 16 minutes ago | |

Like CP/M, DOS v1, RT-11 etc.

VMS used:

    node::device:[dir1.dir2.dir3]filename.extension;version

from memory, you could have up to 15 nested directories.

The versioning was cool as long as you remembered to clean them up.

$ cat <<'EOF' >x.lisp heredoc> (require :uiop) heredoc> (let ((p (make-pathname :name "foo:bar"))) heredoc> (format t "~@{~A~%~}" (namestring p) (uiop:native-namestring p))) heredoc> EOF $ ccl -b -Q -l x.lisp </dev/null foo\:bar foo:bar $ sbcl --script x.lisp foo:bar foo:bar