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Currently actively maintained systems:
- Cygwin. A POSIX layer for Microsoft Windows. Used for Windows UNC paths.
- UWIN since 1.3. Another POSIX layer for Windows. Used at least for
//host/filenetwork file sharing paths.
- @OlivierDulac IBM z/OS as mentioned in the POSIX bug tracker, z/OS resolves
//pathnamerequests to MVS datasets, not to network files. Example.
@BinaryZebra Apollo Domain/OS (confirmed). Also mentioned at Official Description UNC (Universal Naming Convention) as the possible origin of
//host/pathnotations (see also, page 2-15).
According to Donn Terry, it was HP (which acquired Apollo Computers) that pushed for inclusion of that provision in the POSIX spec for Domain/OS.
@jillagre Tektronix Utek (corroborated), where
//host/pathis a path on a distributed file system.
@gilles QNX 4 with the FLEET distributed processing system, where
/pathon node 123. (Mentioned in the QNX 6 documentation.)
@roaima AT&T SysV Release 3 (unverified).
//host/pathin (discontinued in SVR4) RFS Remote File Sharing system.
@Scott SEL/Gould UTX-32 (unverified). Used for
Applications that treat
//foo/bar specially for paths
- @Prem Perforce where
//depot/A/B/C/Drefers to a path in a depot.
- @WChargin Blender. In its configuration you use a
//prefix for relative paths (to the blend associated with the data-block).
- The Bazel build system uses a
//prefix for labels of targets within the Bazel build graph.
Do some applications running on Unix-likes —if not the system’s API— treat //foo/bar Paths specially?
I am aware of Perforce which uses
//depot/A/B/C/D Paths to refer to the Depot.
Perforce also supports
//Client/C/D Paths, when the Client is pointing to
//depot/A/B/. Here, local FileSystem may not have these Paths.
p4 filelog //depot/A/B/C/D will show the history of that file, even though there is no file
p4 filelog C/D will also show the history of that file, if executed from appropriate Directory.
Reference : https://www.perforce.com/perforce/r12.1/manuals/cmdref/o.fspecs.html
Several decades ago, Tektronix Utek (BSD 4.2 based Unix, first on National Semiconductors 32016 CPUs then Motorola 68020s) was providing something called DFS (distributed file system) under which
//foo/bar was referring to the
/bar file on the
foo dfs server. It was later obsoleted by Sun’s NFS.
Unfortunately, I haven’t reference yet to back that but I might eventually find some Utek documentation in my cellar and update this reply.