startx learning notes

I suspect that the GTX "cannot open display" problem is because I do not "startx" before trying to display an image.  Actually I don't know what is startx, except that X might refer to X windows.

To clear my mind, so I googled.


startx(1) - Linux man page

Name

startx - initialize an X session

Synopsis

startx [ [ client ] options ... ] [ -- [ server ] [ display ] options ... ]

Description

The startx script is a front end to xinit that provides a somewhat nicer user interface for running a single session of the X Window System. It is often run with no arguments.

Arguments immediately following the startx command are used to start a client in the same manner as xinit(1). The special argument '--' marks the end of client arguments and the beginning of server options. It may be convenient to specify server options with startx to change on a per-session basis the default color depth, the server's notion of the number of dots-per-inch the display device presents, or take advantage of a different server layout, as permitted by the xorg(1) server and specified in the xorg.conf(5) file. Some examples of specifying server arguments follow; consult the manual page for your X server to determine which arguments are legal.

startx -- -depth 16
startx -- -dpi 100

startx -- -layout Multihead

To determine the client to run, startx first looks for a file called .xinitrc in the user's home directory. If that is not found, it uses the file xinitrc in the xinit library directory.

If command line client options are given, they override this behavior and revert to the xinit(1) behavior. To determine the server to run, startx first looks for a file called .xserverrc in the user's home directory. If that is not found, it uses the file xserverrc in the xinit library directory. If command line server options are given, they override this behavior and revert to the xinit(1) behavior. Users rarely need to provide a .xserverrc file. See the xinit(1) manual page for more details on the arguments.

The system-wide xinitrc and xserverrc files are found in the /etc/X11/xinit directory.

The .xinitrc is typically a shell script which starts many clients according to the user's preference. When this shell script exits, startx kills the server and performs any other session shutdown needed. Most of the clients started by .xinitrc should be run in the background. The last client should run in the foreground; when it exits, the session will exit. People often choose a session manager, window manager, or xterm as the ''magic'' client.

Example

Below is a sample .xinitrc that starts several applications and leaves the window manager running as the ''last'' application. Assuming that the window manager has been configured properly, the user then chooses the ''Exit'' menu item to shut down X.

xrdb -load $HOME/.Xresources
xsetroot -solid gray &
xbiff -geometry -430+5 &
oclock -geometry 75x75-0-0 &
xload -geometry -80-0 &
xterm -geometry +0+60 -ls &
xterm -geometry +0-100 &
xconsole -geometry -0+0 -fn 5x7 &
exec twm
Environment Variables

DISPLAY

This variable gets set to the name of the display to which clients should connect. Note that this gets set, not read.

XAUTHORITY

This variable, if not already defined, gets set to $(HOME)/.Xauthority. This is to prevent the X server, if not given the -auth argument, from automatically setting up insecure host-based authentication for the local host. See the xserver(1) and xsecurity(7) manual pages for more information on X client/server authentication.

Files

$(HOME)/.xinitrc
Client to run. Typically a shell script which runs many programs in the background.

$(HOME)/.xserverrc

Server to run. The default is X.

/etc/X11/xinit/xinitrc

Client to run if the user has no .xinitrc file.

/etc/X11/xinit/xserverrc

Server to run if the user has no .xserverrc file.

See Also

xinit(1), xserver(1), xorg(1)

Referenced By

x11vnc(1), xdesktopwaves(1)




xinit - Wikipedia

Written in C

Website xinit manual page

The xinit program allows a user to manually start an X server. The startx script is a front-end for xinit.

By default, xinit and startx start an X server on display :0 and then start an xterm on it. When the xterm terminates, xinit and startx kill the X server. In general, xinit and startx can start an arbitrary server and run an arbitrary script. Typically, this script runs a number of programs and a window manager.

Two alternative methods for starting an X server are by using a display manager and by starting the X server and then manually starting one or more clients. On desktop Linux systems, using a display manager is the most commonly used method.

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