OS-APPEND statement

Executes an operating system file append command from within ABL.

Syntax


OS-APPEND { `source-filename` \| VALUE ( `expression` ) } { `target-filename` \| VALUE ( `expression` ) }

source-filename

The name of the source file. (If you append file A to file B, file A is the source file.) If you specify a directory, OS-APPEND generates an error.

VALUE ( expression )

An expression that returns the name of the source file. (If you append file A to file B, file A is the source file.) expression can contain constants, field names, and variable names.

target-filename

The name of the target file. (If you append file A to file B, file B is the target file.)

VALUE ( expression )

An expression that returns the name of the target file. (If you append file A to file B, file B is the target file.) expression can contain constants, field names, and variable names.

Example

This procedure opens a dialog box that prompts the user to choose a source file for the append. It then prompts for a name for the target file. Finally, the procedure uses the OS-APPEND statement to append the source file to the target file.

r-os-app.p
DEFINE VARIABLE sourcefile AS CHARACTER NO-UNDO. DEFINE VARIABLE targetfile AS CHARACTER NO-UNDO FORMAT "x(20)" VIEW-AS FILL-IN. DEFINE VARIABLE OKpressed AS LOGICAL NO-UNDO INITIAL TRUE. Main: REPEAT: SYSTEM-DIALOG GET-FILE sourcefile TITLE "Choose Source File For Append" MUST-EXIST USE-FILENAME UPDATE OKpressed. IF OKpressed = FALSE THEN LEAVE Main. UPDATE targetfile WITH FRAME appendframe. OS-APPEND VALUE(sourcefile) VALUE(targetfile). END.

r-os-app.p

DEFINE VARIABLE sourcefile AS CHARACTER NO-UNDO. 
DEFINE VARIABLE targetfile AS CHARACTER NO-UNDO FORMAT "x(20)"  
  VIEW-AS FILL-IN. 
DEFINE VARIABLE OKpressed  AS LOGICAL   NO-UNDO INITIAL TRUE. 
Main: 
REPEAT: 
  SYSTEM-DIALOG GET-FILE sourcefile 
    TITLE "Choose Source File For Append" 
    MUST-EXIST 
    USE-FILENAME 
    UPDATE OKpressed. 
   
  IF OKpressed = FALSE THEN 
    LEAVE Main. 
  UPDATE targetfile WITH FRAME appendframe. 
  OS-APPEND VALUE(sourcefile) VALUE(targetfile). 
END.

Notes

The filenames must conform to the naming conventions of the underlying operating system.

If target-file names a file that does not exist or a directory, OS-APPEND becomes an OS-COPY and a copy is created in the current or specified directory. If an error occurs during the copy, the AVM deletes the partial target-file.

Although an error can occur during execution of this statement, the statement does not generate an error message, raise an error condition, or affect the program’s flow in any way. Check for an execution error by using the OS-ERROR function and evaluating the return.

If you specify the same file for the source and the target, the append fails but OS-ERROR is not set.