Initializing help system before first use

system

system


Purpose
Execute an external program.
Synopsis
procedure system(command:string|text)
Argument
command 
The command to be executed
Example
The following displays the functionality of the mmsystem module using the program mosel:
system('mosel -s -c "exam mmsystem"') 
Further information
1. The given program is executed directly: if the specified expression is a shell command, it is necessary to call the shell explicitly. For instance to get a directory listing under Windows the command will be "cmd /C dir".
2. Using this procedure should be avoided in applications that are to be run on different systems because such a call is always system dependent and may not be portable.
3. The generated process inherits the current system environment plus the environment variables modified/created using the setenv procedure.
4. On Windows the program to execute is located using the current process environment, as a consequence any modification of the PATH environment variable or working directory has no effect on finding this executable. The behaviour is different on Posix systems where the search for the program to execute is performed from the subprocess environment.
5. The default output and error streams of the generated process are redirected to the corresponding Mosel streams. The default input stream is closed.
6. This procedure is included in the published interface of mmsystem (see Section Published library functions).
7. When Mosel is running in restricted mode (see Section mosel command: restricted mode), the restriction NoExec disables this routine unless the environment variable MOSEL_EXECPATH is defined. This variable, used in a similar way as the PATH environment variable, gives a list of paths than can still be used under the restriction. In addition to directories, the definition of the variable may include paths to executables such that it may directly specify a list of programs. It is also worth noting that no search is performed ( i.e. executables must be given with their full path) and that path expansion is performed a the time of loading mmsystem relative to the Mosel initial working directory.
8. The command may be preceded by the prefix "enc:" to specify the encoding of the output streams (see Section Character encoding of text files).
Module