Hello Branden, On Wed, 27 Feb 2019 at 11:42, G. Branden Robinson <g.branden.robinson@xxxxxxxxx> wrote: > > At 2019-02-27T11:21:14+0100, Michael Kerrisk (man-pages) wrote: > > Bjarni, > > > > On 1/1/19 10:51 PM, Bjarni Ingi Gislason wrote: > > > Use '\e' for printing the escape character, not '\\'. > > > > You do not say why such a change is desirable. > > *roff escape sequences may sometimes look like C escapes, but that is > misleading. *roff is in part a macro language and that means recursive > expansion to arbitrary depths. > > You can get away with "\\" in a context where no macro expansion is > taking place, but try to spell a literal backslash this way in the > argument to a macro and you will likely be unhappy with results. > > Try viewing the attached file with "man -l". > > "\e" is the preferred and portable way to get a portable "escape > literal" going back to CSTR #54, the original Bell Labs troff paper. > > groff(7) discusses the issue: > > \\ reduces to a single backslash; useful to delay its > interpretation as escape character in copy mode. For a > printable backslash, use \e, or even better \[rs], to be > independent from the current escape character. > > As of groff 1.22.4, groff_man(7) does as well: > > \e Widely used in man pages to represent a backslash output glyph. > It works reliably as long as the .ec request is not used, which > should never happen in man pages, and it is slightly more > portable than the more exact ‘\(rs’ (“reverse solidus”) escape > sequence. > > People not concerned with portability to extremely old troffs should > probably just use \(rs (or \[rs]), as it means "the backslash > glyph", not "the glyph corresponding to whatever the current escape > character is". Thanks for the great explanation! Since some existing pages already use '\e', I've made the switch to '\e' everywhere. Thanks, Michael -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/
