Why does “rxvt -font x” give me an error, but a “better” font than plain “rxvt”?

Question

When I run rxvt& (Rxvt v2.7.10 - released: 26 MARCH 2003) [which seems old, but is the version that ships with Fedora Core 24], I get an rxvt window with a font I find ugly.

When I do rxvt -font x however, I get the error message rxvt: can't load font "x", but then get an rxvt window with a slightly smaller font that I really like.

What unholy magic is this and how can I do the same thing without getting an error?

I do have rxvt mentioned in some of my .x* files, but nothing that mentions fonts:

• In .Xdefaults, I have:

 
rxvt*background:        grey 
rxvt*foreground:        black 
rxvt*saveLines:         100 
rxvt*geometry:          80x53 

• In .Xresources, I have:

 
rxvt*background:        grey 
rxvt*foreground:        black 
rxvt*saveLines:         60 

• In .fvwm2rc, I have:

 
Style "rxvt"        Icon term.xpm, SloppyFocus, IconBox -70 1 -1 -140 
Style "rxvt"        MWMBorder, MWMButtons 

This is the file I suspect the most, but I don't see anything mentioning font.

NOTE: this has been bugging me for the last 20 years.

Answer 1

rxvt uses "fixed" if the -font option fails. It does this in main.c:

xfont = XLoadQueryFont(r->Xdisplay, r->h->rs[Rs_font + idx]);
if (!xfont) {
    rxvt_print_error(msg, r->h->rs[Rs_font + idx]);
    r->h->rs[Rs_font + idx] = "fixed";
    xfont = XLoadQueryFont(r->Xdisplay, "fixed");
    if (!xfont) {
        rxvt_print_error(msg, "fixed");
        goto Abort;
    }
}
r->TermWin.font = xfont;

The difference is because the default font is not "fixed" (an alias for a specific font), but something like

-misc-fixed-medium-r-semicondensed--12-110-75-75-c-60-iso8859-1

which is different from the actual "fixed"

-misc-fixed-medium-r-semicondensed--13-120-75-75-c-60-iso8859-1

(I used xfd -fn fixed to get the latter, but you could see this in /usr/share/X11/fonts/misc/fonts.alias).