dosinit

Purpose

     Initializes the DOS Services environment.

Library

     DOS Services Library (libdos.a)

Syntax

     #include <dos.h>

     int dosinit ( )

Description

     The dosinit subroutine  initializes the run-time environ-
     ment required by  the DOS Services subroutines.  Programs
     must call the dosinit subroutine  before using any of the
     DOS Services subroutines.

     The  dosinit  subroutine  looks  for  the  initialization
     information in the following places:

     1.  It  attempts to  read the  information from  the file
         named by DOSENVT.   DOSENVT is a variable  in the AIX
         environment.  The dos command (or any parent process)
         creates this file by calling the dosunopen subroutine
         before starting a child process.

     2.  If the DOSENVT variable is not set, then dosinit con-
         figures  DOS Services based  on  the AIX  environment
         variables in the following list.

     3.  For  the  AIX variables  that  are  not defined,  the
         default values shown in the following are used.

     AIX Variable Default Value

     DOS_NUL      /dev/null
     DOS_CON      /dev/tty
     DOS_COM1     /dev/tty0
     DOS_COM2     /dev/tty1
     DOS_AUX      /dev/tty0
     DOS_LP0      /dev/lp0
     DOS_LP1      /dev/lp1
     DOS_LP2      /dev/lp2
      .            .
     DOS_LP7      /dev/lp7
     DOS_A        /dev/fd0

     DOS_B        /dev/fd0
     DOS_C        $HOME
     DOS_D        /
     DOS_E        No default
     DOS_F        No default
      .            .
     DOS_Z        No default.

     Note:  If $HOME is set to  /, or if it is undefined, then
     the default directory for DOS_C is /usr/dos.

     The value  assigned to  each of  these variables  must be
     either:

     o   The full AIX path name of an accessible device, file,
         or directory, or

     o   A string in the form  "|"command, where command is an
         AIX command.  The specified  command receives, as its
         standard input,  the data that  DOS Services programs
         write to the corresponding logical device.

     The dosinit  subroutine also uses the  following environ-
     ment variable:

     DOSDISK      Specifies  the  initial  default  drive  for
                  DOS Services.  If  DOSDISK is not  set, then
                  dosinit searches sequentially  from A: to Z:
                  and  sets the  default  drive  to the  first
                  valid file system found.

     The AIX  environment variables that specify  the DOS Ser-
     vices configuration can be set in the system /etc/profile
     file, in the user's  $HOME/.profile, or directly from the
     AIX command  line.  See the  sh command in  AIX Operating
     System  Commands  Reference  for more  information  about
     setting AIX environment variables,  which are also called
     shell variables.

     The  AIX environment  variables  are  accessed only  once
     during a single session started by the dos command.  From
     then on, internal configuration tables are used.

Return Value

     Upon successful completion dosinit  returns a value of 0.
     Otherwise a value of -1  is returned, and doserrno is set
     to indicate the error.

Related Information

     In  this  book:    "DOS  services  library,"  "dosread,"
     "dosunopen, dosreopen," and  "doswrite."

     The dos and sh commands  in AIX Operating System Commands
     Reference.