FileSwitch Accessing File Systems
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» Part 4 – Using Filing Systems
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Accessing Filing Systems
Filing Systems
Accessing objects within different filing systems can easily be achieved by specifying the file system by suffixing a ‘:’ character to the name of the file system. This is the preferred method of specifying filing systems.
It is also possible to specify filing systems by encapsulating the file system name within the ‘-’ character, but this is not recommended as this character can be used as part of a file name, and hence may cause potential problems.
For example, both commands below would specify the same file within the same filing system.
adfs:$.Documents.Accounts.CashFlow (Preferrred Option)
-adfs-$.Documents.Accounts.CashFlow
Special Fields
Special fields are used to supply additional information to the filing system. For example, NetFS uses them to specify server names or addresses. Special fields are identified by use of the leading ‘#’ character.
net#alan::Disc1.Photos.Sunshine
#alan::Disc1.Photos.Sunshine
-net#alan-:Disc1.Photos.Sunshine
#alan-:Disc1.Photos.Sunshine
Special fields are passed to the filing system as null-terminated strings, with the ‘#’ and trailing ‘:’ or ‘-’ removed (see filing systems above for use of these characters).
Only certain commands can take advantage of special fields. If no special field is specified in a pathname then the appropriate register in the file system routine is set to zero.
The system variable FileSwitch$SpecialField</code is also used to store the special field.
Current Selections
If the filing system is not explicitly stated, then the currently selected one will be used by default. The FileSwitch module is responsible for maintaining a list of file systems and the current selections within each file system. The table below shows the possible selections within each filing system.
| # | Acronymn | CLI char1 | Meaning |
|---|---|---|---|
| 0 | CSD | @ | Currently Selected Directory |
| 1 | PSD | \ | Previously Selected Directory |
| 2 | URD | & | User Root Directory |
| 3 | CSL | % | Currently Selected Library |
1 The character used within the CLI to identify filing system selections.
System Variables
The FileSwitch module provides information relating to filing systems by use of system variables, which as the name suggests are global system-wide variables. Each filing has its own set of system variables, and are case sensitive.
The table below details the system variables available for use.
| Variable | Meaning |
|---|---|
| FileSwitch$CurrentFilingSystem | Current filing system |
| FileSwitch$TemporaryFilingSystem | Temporary filing system |
| FileSwitch$fs$CSD | CSD for filing system fs |
| FileSwitch$fs$PSD | PSD for filing system fs |
| FileSwitch$fs$Lib | Library for filing system fs |
| FileSwitch$fs$URD | URD for filing system fs |
| FileSwitch$SpecialField | Special field (evaluated as path is processed) |