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Re: ot: on stdin, stdout, stderr and crlf on windows

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Meredith Montgomery <mmontgomery@levado.to> writes:
[...]
> You're right.  The Windows situation is reversed when we deal with
> stdin.  If I input \r\n, it replaces to \n if in _O_TEXT.  I totally
> missed that indeed because --- well, it's so confusing.  Thank you.

It's not too confusing once you understand it.

On UNIX, C's original home, text files use LF (ASCII 0x0a), and only
LF, to mark the end of a line in a text file.  So you can read raw
data from a text file and assume that an LF character always marks
the end of a line, and write raw data to a text file and be sure
that each LF written will mark the end of a line.

Other systems use different conventions.  MS-DOS and Windows use
a CR-LF pair, and other systems use other character combinations
or more complicated schemes.  C's <stdio.h> is designed to map all
those variations to a single scheme of using '\n'.  So on input,
the OS's end-of-line marker, whatever it is, is tranlated to '\n',
and on output '\n' is translated to the OS's end-of-line marker.

stdin, stdout, and stderr are all text streams, so operations on them
all perform this mapping, one way or the other.

> By the way, because I used write() and saw the translations taking
> place, I conclude the kernel is doing these translations, not the local
> C library.

I wouldn't assume that.  On Linux/Unix systems, write is usually a
system call implemented by the kernel.  (POSIX just says it's a
function, but it happens to be implemented as a system call on most
Unix-like systems).  On Windows, the write() function is probably
implemented on top of lower-level Windows calls.  On systems where
write() is a system call, it doesn't transform end-of-line markers
because it doesn't need to.

-- 
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
Working, but not speaking, for Philips
void Void(void) { Void(); } /* The recursive call of the void */

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ot: on stdin, stdout, stderr and crlf on windows Meredith Montgomery <mmontgomery@levado.to> - 2021-12-04 20:24 -0300
  Re: ot: on stdin, stdout, stderr and crlf on windows Mike Terry <news.dead.person.stones@darjeeling.plus.com> - 2021-12-05 00:01 +0000
  Re: ot: on stdin, stdout, stderr and crlf on windows Mike Terry <news.dead.person.stones@darjeeling.plus.com> - 2021-12-05 00:13 +0000
    Re: ot: on stdin, stdout, stderr and crlf on windows Meredith Montgomery <mmontgomery@levado.to> - 2021-12-04 23:09 -0300
      Re: ot: on stdin, stdout, stderr and crlf on windows Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-12-04 18:27 -0800
      Re: ot: on stdin, stdout, stderr and crlf on windows Mike Terry <news.dead.person.stones@darjeeling.plus.com> - 2021-12-05 03:33 +0000
        Re: ot: on stdin, stdout, stderr and crlf on windows Meredith Montgomery <mmontgomery@levado.to> - 2021-12-05 09:17 -0300
  Re: ot: on stdin, stdout, stderr and crlf on windows Bonita Montero <Bonita.Montero@gmail.com> - 2021-12-05 15:04 +0100
  Re: ot: on stdin, stdout, stderr and crlf on windows Bonita Montero <Bonita.Montero@gmail.com> - 2021-12-05 15:13 +0100
    Re: ot: on stdin, stdout, stderr and crlf on windows John Forkosh <forkosh@panix.com> - 2021-12-06 08:20 +0000
      Re: ot: on stdin, stdout, stderr and crlf on windows Bonita Montero <Bonita.Montero@gmail.com> - 2021-12-06 09:45 +0100
      Re: ot: on stdin, stdout, stderr and crlf on windows Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-12-06 10:36 +0000
        Re: ot: on stdin, stdout, stderr and crlf on windows Bonita Montero <Bonita.Montero@gmail.com> - 2021-12-06 13:03 +0100
          Re: ot: on stdin, stdout, stderr and crlf on windows Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-12-06 12:34 +0000
            Re: ot: on stdin, stdout, stderr and crlf on windows Manfred <noname@add.invalid> - 2021-12-06 14:38 +0100
              Re: ot: on stdin, stdout, stderr and crlf on windows Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2021-12-06 06:00 -0800
                Re: ot: on stdin, stdout, stderr and crlf on windows Manfred <noname@add.invalid> - 2021-12-06 18:59 +0100
              Re: ot: on stdin, stdout, stderr and crlf on windows Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-12-06 17:08 +0000
                Re: ot: on stdin, stdout, stderr and crlf on windows scott@slp53.sl.home (Scott Lurndal) - 2021-12-06 17:18 +0000
            Re: ot: on stdin, stdout, stderr and crlf on windows John Forkosh <forkosh@panix.com> - 2021-12-07 01:11 +0000
              Re: ot: on stdin, stdout, stderr and crlf on windows Bart <bc@freeuk.com> - 2021-12-07 09:56 +0000
                Re: ot: on stdin, stdout, stderr and crlf on windows John Forkosh <forkosh@panix.com> - 2021-12-08 08:13 +0000
  Re: ot: on stdin, stdout, stderr and crlf on windows Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-12-10 01:10 -0800
    Re: ot: on stdin, stdout, stderr and crlf on windows gazelle@shell.xmission.com (Kenny McCormack) - 2021-12-10 11:00 +0000

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