Status of SGR codes in man pages vs. overstrike in info browser

[Gavin Smith]

Hi,

The info browser can display bold and underline in man pages, but only
if the man program invoked produces output with SGR codes in it. groff
is able to output these codes, and from what research I've done,
current groff releases seem to output them by default. They can be
turned off with by setting an environmental variable GROFF_NO_SGR, and
it will produce overstrike codes instead (e.g. "x" backspace "_" for
an underlined "x" character.)

However, it seems that many distributions of groff turn this off by
default. They instead require the variable GROFF_SGR to be set.
(However, there isn't any or very much documentation of this: I looked
through the groff manual and didn't understand why they weren't being
output.)

The end result of this is that most users, I would expect, would not
get bold and underlining when viewing man pages in info, and would not
realise that it is actually possible. So I'm suggesting that maybe
some kind of note to this effect could be placed in the manual. I'm
not sure what, however. The simple answer is to say to run "export
GROFF_SGR=1" to get them, but the use of this variable is not
official.

Any ideas?

Gavin