Resolution of Variables

Variables are generally resolved when executing eScripts or, for example, during an internal program flow.

The following rules apply:

  • Every variable between percent signs is replaced by its current value (%Name% is therefore replaced by the value of the Name variable).
     Example:
     %ServerProperties.NetInstallDir% is replaced by the value of the respective setting DSM share on the depot, i.e. \\DSMServer\DSM$\
  • An “empty“ variable is replaced by a percent sign.
     Example:
     %% is replaced by %
  • If the value of a variable contains another variable, the other variable will also be resolved. This process is repeated until there is no variable left.
     Example:
    If the value of the setting DSM share on the depot in the example above is \\%CurrentServer%\DSM$\ and %CurrentServer% is DSMServerMain, the variables are resolved in the following manner:
     %ServerProperties.NetInstallDir% is resolved to \\%CurrentServer%\DSM$\
     \\%CurrentServer%\DSM$\ is resolved to \\DSMServerMain\DSM$\

Using Brackets with Variables

The rules above imply that a pair of two percent signs are generally interpreted as a variable; independent of the characters between the percent signs.
Therefore it is not possible to enter another variable directly in an existing variable.

Example:
An eScript contains the variables %DSMServer1%, %DSMServer2% etc. and %Number%.
In the following process, the system uses the variable %DSMServer%Number%%.
According to the logic explained above, the system would find the variables %DSMServer%Number%% and %% for resolution in the variable %DSMServer%. Since %DSMServer% does not exist as a variable in this case, the variable cannot be resolved.
The following requirement should be met instead: first, to resolve the %Number% variable to the value 1, for example, and then to resolve the resulting variable %DSMServer1%.

There are two solutions for meeting this requirement:

  • Defining variables and auxiliary variables separately before employment:
     Set (Number,1)
     Set (DSMServerNumber,%%DSMServer%Number%%%) (after being resolved, the variable has the value %DSMServer1%)
     .....
     .....%DSMServerNumber%.....
  • Using brackets:
     .....
     .....%[DSMServer%Number%]%..... (after being resolved, the variable also has the value %DSMServer1%)

    • If you use brackets, the variable in brackets is resolved first; then, the resulting variable is resolved.
    Using this syntax helps you avoid defining auxiliary variables (this process is less complex).

Backslashes in Variable Values

When the value of a variable is interpreted, DSM eliminates the trailing backslash "\". This prevents double backslashes from appearing in paths.

Example:
Use the following path defined with the variable _Userdirectory: %Userdirectory%\TEST.
If you assign _Userdirectory the value C:\WINNT\User\, NetInstall interprets the path as follows: C:\WINNT\User\TEST, , which does not work for: C:\WINNT\User\\TEST.

Checking and Resolving Variables During Resolution

You can specify alternative values for variables that cannot be resolved as required.

There are two cases in which DSM supports using alternative values:

  • if a variable cannot be be resolved in general
  • if a variable is not an integer

The syntax in the first case is: %[~<variable>~<alternative value>]%

This means that if the specified <variable> cannot be resolved, the specified <alternative value> is used.

Examples:
 %[~CurrentComputer.Var.Settings.Value~1]%
If the specified DSM variable is not set, the alternative value 1 is used.
 %[~ProgramData~C:\ProgramData]%
If the environment variable ProgramData is not available on a computer, the alternative value is used instead.

The syntax in the second case is: %[~(int)<variable>~<alternative value>]%

This means that if the specified <variable> is not an integer after resolution, the specified <alternative value> is used.

Examples:
 %[~(int)FreeSpace~0]%
This ensures that there is another number available for calculation after resolving the variable.
 %[=1 max %[~(int)percent~50]% min 100]%
This ensures that there is a number between 1 and 100 available after resolving the variable; if the number is not valid, 50 is used.