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Automatically configuring the DISPLAY environment variable

With X-Win32 you do not have to set the $DISPLAY environment variable in your login scripts (e.g. .bashrc, .cshrc, or .profile) on your remote UNIX, Linux, or BSD hosts (e.g. Red Hat, SuSE, Debian, Ubuntu, HP-UX, AIX, or Solaris) in order for the program in the command field of your X-Win32 sessions to work. In fact, setting this environment variable in your login scripts will most likely cause your X-Win32 sessions to work only when you connect from one of your Windows machines.

There are two different tactics for avoiding setting the $DISPLAY environment variable, depending on the type of session that you are using.

Avoiding setting $DIPSLAY for rexec and rsh sessions

  1. If your remote host is on the same network (i.e. there are no firewall or network address translation (NAT) devices between your two hosts) as your X-Win32 machine, then simply add the -display $DISPLAY command-line parameter to your X-Win32 sessions using X-Config, then remove all traces of setting $DISPLAY from your login scripts.
  2. If there is a firewall or NAT device between the two computers and the remote computer is on the public Internet, then you can use X-Win32’s IPSmart facility to find the address of your NAT device; to do this, simply add the -display $IPSMART:$DNUM command-line paramter to your X-Win32 sessions using X-Config, then remote all traces of setting $DISPLAY from your login scripts. If all of your sessions function this way, then you can instead change the address in X-Config’s Display tab to IPSmart, which will cause -display $DISPLAY to return the IPSmart address.
  1. For newly created sessions, be sure to use the Wizard button in X-Config’s Sessions tab to create each session. The Session Wizard automatically adds the -display $DISPLAY command-line parameter to new rsh and rexec sessions that start xterm or dtterm.

    Avoiding setting $DISPLAY for StarNetSSH sessions

  2. If you are not using X11 Forwarding with your StarNetSSH sessions (e.g. because it is disabled in sshd_config on the remote host), then you should first and foremost turn this feature on as it will automatically set the $DISPLAY environment variable on the remote host for you, without the need to pass -display [...] on the command-line to your sessions.
  1. If you are using X11 Forwarding with your StarNetSSH sessions but the $DISPLAY environment variable seems to be incorrect (noted by a cannot open display error when starting your StarNetSSH sessions) then you need to double-check your login scripts to be sure that they are not setting the $DISPLAY environment variable and thus overriding the value that sshd is setting it to.

    Category:Sessions -> rexec
    Category:Sessions -> rsh
    Cateogry:Sessions -> StarNetSSH



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