Don Cragun wrote: > From: "Garrett D'Amore" <gdamore at sun.com> > > I. Szczesniak wrote: > ... ... ... > >> Could you elaborate the difference between Committed and Committed > >> Obsolete? > >> > > > > Committed Obsolete means we can't remove it, but you're still > > discouraged from using it in new code. That's the case with -b -- it is > > used to indicate a count in blocks (512 bytes), but the option was > > removed from the POSIX standard over confusion about what was meant by a > > "block" (is it a block of bytes, or a block of characters?) > > > ... ... ... > > > > -- Garrett > > Garrett, > I think you misread the tail rationale in the POSIX standard. > SVID3 had a -b option that counted 512-byte blocks; BSD had a -b option > that counted 1024-byte blocks. The -b option wasn't removed from POSIX; > it was never added in the first place due to this difference in > behavior.
Erm... that was my fault... I thought that "-b" was defined by POSIX long long ago. Sorry about that. > The SVID3 and XPG3 -c options counted in bytes, but the documentation > said it counted characters (I don't remember what the BSD tail man page > said). The POSIX committee briefly considered changing the -c option to > be -b when the description of -c changed from "characters" to "bytes", > but left it as -c because historical implementations had the -b option > counting blocks even though it wasn't going to be specified by the > standard. > > The standard does not currently specify a way to count (multi-byte) > characters even though this means tail output may start or end in the > middle of a multi-byte character when using the -c option. Is this even possible to specify characters in this case ? AFAIK the multibyte API doesn't have a way to seek into a random position in a file and then find the start of the next multibyte character (it works for UTF-8 but I am not sure for older encoding systems). ---- Bye, Roland -- __ . . __ (o.\ \/ /.o) roland.mainz at nrubsig.org \__\/\/__/ MPEG specialist, C&&JAVA&&Sun&&Unix programmer /O /==\ O\ TEL +49 641 3992797 (;O/ \/ \O;)
