Single colon in Path

Hi,

can someone please explain what a single colon in a path means?

As an example, consider the following command

Cat C:

This outputs the content of SDFS::HardDisc0.$.AcornC/C++.Export.APCS-32.Lib.clib.

Where does this come from and where is it defined?

At first i thought it may have something to do with the system variable C$Path which also includes the above path, but has additional directories too, delimated with a comma. Additionally, the CLI is “normally” expanding system variables enclosed with <>.

Thanks,
Egon

Doesn’t do that for me.
Cat Mac
displays as expected
but
cat Mac:
gives
Filing system or path Mac: not present

The trailing colon defines the variable as a path. C: is the syntax for C$Path.

*Cat only lists the objects in a directory. If it is asked to catalogue a path only the contents of the first directory on the path are shown.

*Help Cat
==> Help on keyword Cat
*Cat lists all the objects in a directory (default is current directory).
Syntax: *Cat [<directory>]
*
*cat c:
Dir. ADFS::Titan4.$.Progm.AcornC/C++.AcornC/C++.Export.APCS-32.Lib.clib Option 02 (Run)
CSD  ADFS:"Unset"
Lib. ADFS:"Unset"
URD  ADFS:"Unset"
h            D/      o            D/
*
*show c$Path
C$Path : ADFS::Titan4.$.Progm.AcornC/C++.AcornC/C++.Export.APCS-32.Lib.clib.,ADFS::Titan4.$.Progm.AcornC/C++.AcornC/C++.Export.APCS-32.Lib.tboxlibs.,ADFS::Titan4.$.Progm.AcornC/C++.AcornC/C++.Export.APCS-32.Lib.c++lib.,ADFS::Titan4.$.Progm.AcornC/C++.AcornC/C++.Export.APCS-32.Lib.flexlib.,ADFS::Titan4.$.Progm.AcornC/C++.AcornC/C++.Export.APCS-32.Lib.

C$Path is set in AcornC/C++.AcornC/C++.!SetPaths.SetPaths

Set C$Path    <CLIB$Path>,<Lib$Dir>.tboxlibs.,<Lib$Dir>.c++lib.,<Lib$Dir>.flexlib.,<Lib$Dir>.

If you have some characters preceding a colon, FileSwitch will first attempt to match it to a registered filing system. If that fails, it then looks up the whatever$Path variable. If that fails, you will get a Filing system or path whatever: not present error.

For the path variable case, FileSwitch may use just the first element of the path (e.g. *Cat, or when using SWI OS_File 0 to save a file) or on each element of the path in turn (e.g. SWI OS_File 5, when looking for C:o.Stubs).

[David beat me to it!]

C$Path is the right place for you to look. It’s what’s called a “path variable”; if a file path starts with a name and a single colon (e.g. Foo:), then FileSwitch will append “$Path” to the name and look to see if there’s a system variable with the same name (e.g. Foo$Path).

If the variable exists, it’s treated as a comma-separated list of paths to search for files in, with each element ending in a dot. E.g. if Foo$Path is defined as SDFS::HardDisc0.$.Bar.,SDFS::HardDisc0.$.Wibble. then trying to access the file Foo:Boop will first look for SDFS::HardDisc0.$.Bar.Boop and then look for SDFS::HardDisc0.$.Wibble.Boop.

Note that filesystems can also be accessed using the single-colon syntax – in which case FileSwitch will try looking in the last selected directory for that filesystem (the isn’t a global “currently selected directory” – it’s actually tracked on a per-filesystem basis)

[Edit: Wait for a useful answer and then 3 turn up at once]

To be fair, path variables aren’t given much coverage in the User Guide.

Thank you very much, makes sense now!

If you have some characters preceding a colon, FileSwitch will first attempt to match it to a registered filing system. If that fails, it then looks up the whatever$Path variable.

I think Jeffrey’s explanation is more correct, because… you know there’s some twit that will test this.
<fx: enthusiastically waves hand in air>

*Set SDFS$Path SCSI::0.$
*Cat SDFS:
Dir. SCSI::MyCache.$ Option 02 (Run) 
CSD  SCSI:"Unset"
Lib. SCSI:"Unset"
URD  SCSI:"Unset"
!MangaLib                             D/      backup                                D/
Moulinex 12 en 1/pdf                  WR/     Philips HD4726 multicooker manual/pdf WR/
*Cat SDFS:$
Directory 'SDFS:$' not found
*Unset SDFS$Path
*Cat SDFS:$
Dir. SDFS::RISCOSPi.$ Option 02 (Run) 
CSD  SDFS:"Unset"
Lib. SDFS:"Unset"
URD  SDFS:"Unset"
!Boot                                 D/WR    Apps                                  D/WR   
AudioVideo                            D/      Coding                                D/     
DebugTools                            WR/     DiscKnight                            WR/WR  
Diversions                            D/WR    Documents                             D/WR   
MyApps                                D/      MyDocuments                           D/     
Printing                              D/WR    random                                D/     
Utilities                             D/WR    Zap                                   D/WR   
_fetchdump                            WR/     _flightradar24                        WR/    
*

Ha ha! Looks like it just turned out to be more convenient to evaluate it in that order…