SoloCodigo

Usa esto :
Dim ret As Long
ret = Shell("c:\program files\winrar\rar a -ap c:\test.rar -ptest c:\answer.txt c:\test.xml")


= OPEN_FILE("c:\program files\winrar\rar a -ap c:\test.rar -ptest c:\answer.txt c:\test.xml")



Con la API ShellExecute.

FUNCTION OPEN_FILE(pcFileName,pcAction,pcParams,pcDefDir,pnShowWindow )
****************************************************
* Filename
If Vartype(pcFileName) <> "C"
   MessageBox("Need a file to open!")
   Return 0
Endif

* Action
If Vartype(pcAction) <> "C"
   pcAction = "open"
Endif

* Parameters
If Vartype(pcParams) <> "C"
   pcParams = ""
ENDIF

* Default Directory
If Vartype(pcDefDir) <> "C"
   pcDefDir = ADDBS(SYS(5)+CURDIR())
ENDIF

* Show Window (min / Max etc)
If Vartype(pnShowWindow) <> "N"
   pnShowWindow = 1
Endif

#Define SE_ERR_FNF 2
#Define SE_ERR_PNF 3
#Define SE_ERR_ACCESSDENIED 5
#Define SE_ERR_OOM 8
#Define SE_ERR_DLLNOTFOUND 32
#Define SE_ERR_SHARE 26
#Define SE_ERR_ASSOCINCOMPLETE 27
#Define SE_ERR_DDETIMEOUT 28
#Define SE_ERR_DDEFAIL 29
#Define SE_ERR_DDEBUSY 30
#Define SE_ERR_NOASSOC 31
#Define ERROR_BAD_FORMAT 11

Declare Integer ShellExecute In shell32.Dll ;
INTEGER hndWin, ;
STRING cAction, ;
STRING cFileName, ;
STRING cParams, ;
STRING cDir, ;
INTEGER nShowWin

cFileName = pcFileName
cAction = pcAction
cParams = pcParams
cDir = pcDefDir
nShowWin = pnShowWindow

Local lnRetVal
lnRetVal = 0
lnRetVal = ShellExecute(0,cAction,cFileName,cParams,cDir,nShowWin)

If lnRetVal <= 32
   Local msg
   msg = ""
   *There was an error
   Do Case
      Case lnRetVal = SE_ERR_FNF
         msg = "File not found"
      Case lnRetVal = SE_ERR_PNF
         msg = "Path not found"
      Case lnRetVal = SE_ERR_ACCESSDENIED
         msg = "Access denied"
      Case lnRetVal = SE_ERR_OOM
         msg = "Out of memory"
      Case lnRetVal = SE_ERR_DLLNOTFOUND
         msg = "DLL not found"
      Case lnRetVal = SE_ERR_SHARE
         msg = "A sharing violation occurred"
      Case lnRetVal = SE_ERR_ASSOCINCOMPLETE
         msg = "Incomplete or invalid file association"
      Case lnRetVal = SE_ERR_DDETIMEOUT
         msg = "DDE Time out"
      Case lnRetVal = SE_ERR_DDEFAIL
         msg = "DDE transaction failed"
      Case lnRetVal = SE_ERR_DDEBUSY
         msg = "DDE busy"
      Case lnRetVal = SE_ERR_NOASSOC
         msg = "No association for file extension"
      Case lnRetVal = ERROR_BAD_FORMAT
         msg = "Invalid EXE file or error in EXE image"
      Otherwise
         msg = "Unknown error"
   Endcase
   RETURN .F.
Else
   Return .T.
Endif

ENDFUNC

La serie 1:
2 Variables una que comienza en impar y otro en par. avanza de 2 en 2

podria ser un for

var1= -1
var2=2
for k=1 to nlimite
   var1 = var1 - 2
   var2 = var2 + 2
next

Serie 2
Cada 4 veces  Duplica el ultimo nro.. y de alli continua..
l_contador = 0
for k=1 to ?nvalor
    l_contador = l_contador + 1
    imprimir k

   if l_contador = 4 then
    imprimir duplicado de k
   l_contador = 0
  endif
next

Serie 3

Avance y retroceso.. tarea para ti