Hi, Alex! At 2021-11-02T19:07:05+0100, Alejandro Colomar (man-pages) wrote: > I was using xface termincal, but I tried on xterm after your email and > see the same result. IF you have a big enough font size and print > them almost together, you'll be able to see the difference: > > $ cat underscore.7test > .TH UNDERSCORE 7TEST today > .SH UNDERSCORE > .RB [ U ] INT \fIN\fP _WI_DTH RO_MAN > > There are 3 different underscores: italics, bold, and roman, > respectiely. At least with the less pager. more doesn't even > highlight, so I can't test with a different pager. > > I used `man ./underscore.7`.
You might want to make sure man(1) isn't confounding the issue--or that a vendor release of groff isn't. Before I get to that I'll share my output. I don't see 3 different underscores, just 2. I don't trust my ageing eyes, however, so I checked a hex dump. $ groff -T utf8 -man EXPERIMENTS/underscore-colomar.7 | xxd 00000000: 554e 4445 5253 434f 5245 2837 5445 5354 UNDERSCORE(7TEST 00000010: 2920 2020 2020 2020 2020 2020 2020 2020 ) 00000020: 2020 2020 2020 2020 2020 2020 2020 2020 00000030: 2020 2020 2020 2020 2020 2020 2055 4e44 UND 00000040: 4552 5343 4f52 4528 3754 4553 5429 0a0a ERSCORE(7TEST).. 00000050: 0a0a 1b5b 316d 554e 4445 5253 434f 5245 ...[1mUNDERSCORE 00000060: 1b5b 306d 0a20 2020 2020 2020 5b1b 5b31 .[0m. [.[1 00000070: 6d55 1b5b 3232 6d5d 1b5b 316d 494e 541b mU.[22m].[1mINT. 00000080: 5b34 6d1b 5b32 326d 4e1b 5b32 346d 1b5b [4m.[22mN.[24m.[ 00000090: 316d 5f57 495f 4454 481b 5b32 326d 524f 1m_WI_DTH.[22mRO 000000a0: 5f4d 414e 0a0a 0a0a 2020 2020 2020 2020 _MAN.... 000000b0: 2020 2020 2020 2020 2020 2020 2020 2020 000000c0: 2020 2020 2020 2020 2020 2020 2074 6f64 tod 000000d0: 6179 2020 2020 2020 2020 2020 2020 2020 ay 000000e0: 2020 2020 2055 4e44 4552 5343 4f52 4528 UNDERSCORE( 000000f0: 3754 4553 5429 0a 7TEST). (This is groff 1.22.4 as shipped by Debian, which somewhat notoriously messes with grotty's SGR default when the groff man(7) macro package is used[1]. I've changed my /etc/man.local to conform with groff upstream.) We can see from the above that no escape sequence is emitted between the first and second underscores. Nor, given the semantics of the 'RB' macro and the input, would I expect there to be. > .RB [ U ] INT \fIN\fP _WI_DTH RO_MAN I think it is pretty clear that both underscores in "_WI_DTH" should render in the same style. To figure out which, admittedly you have to count arguments (you can just count mod 2 as in "eeny meeny miney moe" if you want to be sophisticated about it ;-) ). Maybe I found the problem. If I run "groff -man -P-c | less -R" inside script(1), to defeat less(1)'s valiant attempts to hide from me the escape sequences it outputs to the terminal, and then hex dump the result, I see (among irrelevant output) the following. 00000400: 554e 4445 5253 434f 5245 2837 5445 5354 UNDERSCORE(7TEST 00000410: 2920 2020 2020 2020 2020 2020 2020 2020 ) 00000420: 2020 2020 2020 2020 2020 2020 2020 2020 00000430: 2020 2020 2020 2020 2020 2020 2055 4e44 UND 00000440: 4552 5343 4f52 4528 3754 4553 5429 1b5b ERSCORE(7TEST).[ 00000450: 6d0d 0a1b 5b6d 0d0a 1b5b 6d0d 0a1b 5b6d m...[m...[m...[m 00000460: 0d0a 1b5b 316d 554e 4445 5253 434f 5245 ...[1mUNDERSCORE 00000470: 1b5b 306d 1b5b 6d0d 0a20 2020 2020 2020 .[0m.[m.. 00000480: 5b1b 5b31 6d55 1b5b 306d 5d1b 5b31 6d49 [.[1mU.[0m].[1mI 00000490: 4e54 1b5b 306d 1b5b 346d 4e5f 1b5b 3234 NT.[0m.[4mN_.[24 000004a0: 6d1b 5b31 6d57 495f 4454 481b 5b30 6d52 m.[1mWI_DTH.[0mR 000004b0: 4f5f 4d41 4e1b 5b6d 0d0a 1b5b 6d0d 0a1b O_MAN.[m...[m... 000004c0: 5b6d 0d0a 1b5b 6d0d 0a20 2020 2020 2020 [m...[m.. 000004d0: 2020 2020 2020 2020 2020 2020 2020 2020 000004e0: 2020 2020 2020 2020 2020 2020 2020 746f to 000004f0: 6461 7920 2020 2020 2020 2020 2020 2020 day 00000500: 2020 2020 2020 554e 4445 5253 434f 5245 UNDERSCORE 00000510: 2837 5445 5354 291b 5b6d 0d0a 1b5b 376d (7TEST).[m...[7m Addresses 0x490 through 0x4af are of particular interest. We see at 0x49c that underlining is turned off, and at 0x4a1 that bold is turned on[2]. So in contrast to the earlier output above, the two underscores in "_WI_DTH" *are* in fact formatted differently. My guess is that what is happening here is a combination of (A) Debian's default of forcing grotty(1) to its legacy output mode when rendering man pages and (B) less(1)'s heuristic about how ambiguous legacy output sequences should be formatted guessing wrongly. I've made explicit notice of this in a recent groff commit.[3] I acknowledge that people have thundered with fundamentalist fervor[4] for years about how legacy output is better, but their preferences simply do not align with what nearly all terminal emulators--on Unix or perhaps anywhere--do or were designed to do. Terminal emulators on Unix were written mostly to emulate video terminals[5], not Teletype machines. Such paper-based devices could progressively saturate paper with ink and therefore had, in practice, multiple "intensity" levels as well as true glyph overstriking. Space would appear to exist for a teletypewriter analogue of CoolRetroTerm[6], for those who want to view their Unix manuals as Ken and Dennis would--nay, MUST--have preferred[4][6][8]. Regards, Branden [1] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=963490 [2] https://invisible-island.net/xterm/ctlseqs/ctlseqs.html [3] https://git.savannah.gnu.org/cgit/groff.git/commit/?id=469ef4fb84ac41a1db430dcf09ee52e9683332c3 [4] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=312935 [5] I note xterm's storage-tube display emulation mode for the Tektronix 4014, and that it doesn't affect the argument. [6] I know what would happen with these people. You could post a 15-second TikTok video of Ken Thompson himself happily clicking through Deri James's WebManPDF site[7], and after about the same interval of their faces bluescreening, you'd hear from them about how even the greatest among us can flag in their fidelity to rightness, and that it's up to the Pure Few possessed of Truth to keep the Faith in the Eternal Model 37. [7] http://chuzzlewit.co.uk/WebManPDF.pl/man:/1/groff [8] The appellants to authority in these case always seem to labor in complete ignorance of the Blit terminal[9]. My guess is that this is because the Blit came just a little too late, after these intellectual feudalists shifted their vassalage from Thompson and Ritchie to Bill Joy. Why? Because Joy was better at making money. [9] https://en.wikipedia.org/wiki/Blit_(computer_terminal)
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