Most of the X11 Display Managers, such as XDM, sddm, gdm etc, are redirecting diagnostic
output (standard error, stderr, file descriptor 2) into a file or some logging facility.
This file is usually $HOME/.xsession-errors
. When "Watch Errors" item
is launched from default subpanel 7 (Desktop Settings), it will execute xterm -e $[infostore.xlogcmd]. If not redefined in $FVWM_USERDIR/NsCDE.conf
,
contents of the variable FVWM infostore variable $[infostore.xlogcmd]
will be
"tail -300f ~/.xsession-errors".
If your X Display Manager is using
different path or file name, this can be redefined as it is mentioned above. Beware that some
X Display Managers (namely lightdm) are sending diagnostic output into
/dev/null
. In this case, no variable redefinition can get this
output visible to the user.
Reading X, FVWM and NsCDE log output can be informative and helping while solving possible unexpected or unexplainable problems with desktop setup.
Window Options menu (called by titlebar button 1, leftmost) of the "Watch Errors" window under FVWM 2.X has a custom menu entry
which starts FVWM module FvwmConsole. FvwmConsole on the other hand has custom menu entry which calls Watch errors. When both windows are on the screen, this menu entries will simply transfer focus to each other.