Red: Execute external and shell command

shell-command.red

http://www.red-by-example.org/#call
The word call executes a shell command to run another process. 
      
The argument is:

     A command   [string! file!]  - A shell command or an executable file. 

Refinements
     /wait  - Runs command and waits for exit. 
     /show  - Force the display of system's shell window (Windows only). 
     /console  - Runs command with I/O redirected to console (CLI console only at present). 
     /shell  - Forces command to be run from shell. 
     /input  - we provide a [string! file! binary!], which will be redirected to stdin.
     /output - we provide a [string! file! binary!] which will
receive the redirected stdout from the command. Note that the
output is appended.
If you don't want this, clear the destination(or delete the file, for example).

     /error - as /output, but redirects stderr.
(Awaiting additional documentation by red-by-example team.)
                                              
                                              
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                                              https://www.rosettacode.org/wiki/Execute_a_system_command#Red
                                              
                                              
                                              REBOL
; Capture output to string variable:
 
x: ""  call/output "dir" x
print x
 
; The 'console' refinement displays the command output on the REBOL command line.
 
call/console "dir *.r"
call/console "ls *.r"
 
call/console "pause"
 
; The 'shell' refinement may be necessary to launch some programs.
 
call/shell "notepad.exe"
Red
 
call/show %pause        ;The /show refinement forces the display of system's shell window (Windows only).
call/show %dir
call/show %notepad.exe