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I am having trouble finding this information, and trial and error is telling me that there may not be any. What are invalid characters for a file name on OS X Lion (10.7)?
Rodney Foley
Posted 2011-08-21T19:32:12.500
Reputation: 332
What are invalid characters for a file name under OS X?
Answers
8
tobylane
Posted 2011-08-21T19:32:12.500
Reputation: 1 271
3Techincally the HFS+ file system does allows all Unicode characters (since it represents names internally as Pascal strings with a 2-byte length), but AFAIK none of the APIs provided by OS X allow you create/open files with a slash '/' or NUL '\0' in them. – Adam Rosenfield – 2011-08-21T20:54:58.620
APIs as in Carbon or Cocoa? I assume Terminal is under such restrictions, but what about scripts run by other programs, such as launchd? – tobylane – 2011-08-21T20:58:19.950
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What are invalid characters for a file name under OS X?
Allowed characters in filenames Unicode, any character, including NUL. OS APIs may limit some characters for legacy reasons
Finder doesn't currently allow entering colons in in file names, but it does allow entering backslashes. However the characters shown as slashes in Finder are shown as colons in shells, and vice versa. Finder doesn't allow any ASCII control characters either.
Bash seemed to allow all control characters except \000 (NUL). I tested it by running the output from:
for i in {1..31} 127 0; do echo touch \\$(bc <<< "obase=8;$i"); done
Lri
Posted 2011-08-21T19:32:12.500
Reputation: 34 501
Could you test / (POSIX path separator) and : (HFS path separator) with bash? – Cœur – 2020-02-05T07:21:31.253
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EDITED
According to Wikipedia, the only invalid character is the forward-slash /, but at the UNIX layer.
2So, no forward slash (/) or colons (:) to be safe? – Nicolas Miari – 2016-02-16T12:07:04.687
2@NicolasMiari Yes. Finder.app won’t allow you to enter a colon, and won’t work properly with filenames that contain it. The UNIX layer won’t allow you to work with files containing a slash (or rather; it translates it to a colon). And then there are other applications (such as Microsoft Word) who choke on either. For instance, if you save a document in TextEdit.app under the filename foo/bar.docx (which works), Microsoft Word will be unable to open it. – Konrad Rudolph – 2016-05-20T14:07:02.310
2Maybe : is prohibited on Mac OS Classic, but certainly not on Mac OS X—touch foo:bar works perfectly fine. – Adam Rosenfield – 2011-08-21T20:56:15.543
1Answer has been updated. You're welcome to remove your downvote. – None – 2011-08-21T21:38:12.257
5@Adam: : is valid in the “unix layer”, but it is translated to/from / in the “Mac layers” (i.e. Finder, most file-related dialogs, etc.): the colon is used as the separator in “HFS paths” and the slash is used as the separator in “POSIX paths” so there is a two-way translation depending on which “layer” you are working with. – Chris Johnsen – 2011-08-22T04:33:01.377
1Single forward slash ? Single backslash ? Single or double period ? – None – 2011-08-21T19:35:51.517
All the slash combo's and singles seem to work, but a single and double period do fail because they are already in use. I hope there is more than that.... :) – Rodney Foley – 2011-08-21T19:43:15.947
You can't use an ASCII NUL. Think a while and you might spot why yourself… – Donal Fellows – 2011-08-21T19:45:06.287
@Donal ASCII NUL is not something you can easily just "type" or do problematically by mistake. – Rodney Foley – 2011-08-21T19:48:47.523
@rodney what on earth has what you can easily type by accident got to do with anything. Do you want help or not?! Sheesh! – David Heffernan – 2011-08-21T19:54:07.533
1Can you give us some context, Rodney? It would help a lot in answering this if we understood a little bit about what you're trying to do... AFAIK, there are a few potential issues: honest-to-god forbidden characters, characters that are impossible to enter as a path in a terminal shell, and characters that won't display properly in Finder. – Shog9 – 2011-08-21T20:03:19.300
Looking for the Apple doc that give's the specifics of what is legal or not thats really it. I can find MSDN Doc's on Windows, and ones for each Linux platform about this, but nothing from Apple I can find. Its a simple question that context shouldn't really matter if you know the answer, if you do not then do not comment or try to answer its simple. – Rodney Foley – 2011-08-21T20:20:05.070
It's built on BSD, so my educated guess would be "it's the same as UNIX". Check my answer, though. – None – 2011-08-21T20:37:03.440
@Rodney: The key point I was making is that NUL is illegal, precisely because it is the marker for the end of the filename. – Donal Fellows – 2011-08-22T09:31:30.437