SAP Basis Tech Supports

Symptom
When you define an external command, you have the option of using certain special characters in the parameter field (for the static parameters).
Other terms
External command, parameter substitution, SM69, SM49
Reason and Prerequisites
There is no error.
Solution
The following special characters are available:
1. ? (question mark)
This character represents a mandatory parameter.
Therefore, if there is a ? character in the static parameters, you have to specify a dynamic parameter during the call. This dynamic parameter is then used automatically instead of the ? character.
2. & (ampersand)
This character represents an optional parameter.
3. < > (angle brackets)
You can enter a logical directory name in angle brackets. The actual directory name then replaces this.
4. $ (dollar)
Using this character, you can replace the name of a profile parameter with its current value. So that the end of the profile parameter name is recognized, the parameter name must be encased by an additional character (it can be any character).
For example: $-rdisp/mshost-