Operating System Functions

Statements and procedures for working with files, directories and the 
system.

Description
   The statements and procedures listed here provide access to the 
   operating system environment. They transfer execution to external 
   programs, get information about files and directories, manipulate the 
   file system and send commands to the command shell.

Working with Files
   Procedures that deal with files.
Working with Directories
   Various directory management procedures.
File Properties
   Get information about files.
System Procedures
   Procedures for working with the environment.

Working with Files
   Exec and Chain
      Temporarily transfers control to another program.
   Run
      Transfers control to another program.
   Kill
      Deletes an existing file.
   Name
      Renames an existing file.

File Properties
   FileAttr
      Gets information about a file bound to a file number.
   FileCopy
      Copies a file.
   FileDateTime
      Gets the last modified date and time of a file.
   FileExists
      Tests for the existence of a file.
   FileLen
      Gets the length (in bytes) of a file.
   FileSetEof
      Sets the length of an open file bound to a file number.
   FileFlush
      Flushes application or system buffers for an open file bound to a 
      file number.
Working with Directories
   CurDir
      Gets the current working directory.
   ChDir
      Sets the current working directory.
   Dir
      Gets the names of files or directories matching certain attributes.
   ExePath
      Gets the directory of the current running program.
   MkDir
      Creates a new directory.
   RmDir
      Deletes an existing directory.

System Procedures
   Fre
      Gets the amount of free memory (in bytes) available.
   Command
      Gets the command-line parameters passed to the program.
   Environ
      Gets the value of an environment variable.
   IsRedirected
      Checks whether stdin or stdout is redirected to a file or not.
   SetEnviron
      Sets the value of an environment variable.
   Shell
      Sends a command to the system command interpreter.
   System
      Closes all open files and exits the program.

