On Tue, Apr 7, 2015 at 4:06 PM, Cameron Simpson <c...@zip.com.au> wrote: > On 07Apr2015 20:38, Chris Angelico <ros...@gmail.com> wrote: >> >> On Tue, Apr 7, 2015 at 3:48 PM, Cameron Simpson <c...@zip.com.au> wrote: >>> >>> The operating system arranges the commection of the shell to the >>> terminal. >>> Your usual program has by default a stdin, stdout and stderr. These are >>> _all_ the same file handle, duplicated to each of the three file >>> descriptors >>> 0, 1 and 2 respectively. On the operating system side, the OS has >>> performed >>> _one_ open() call on the terminal device and handed the caller a single >>> file >>> descriptor. The caller then calls dup() (or modernly, dup2()) to present >>> the >>> open terminal as stdin, stdout and stderr. >> >> >> Really? I can believe that stdout and stderr are initially duplicates, >> but stdin as well? Isn't stdin opened for reading only, and >> stdout/stderr for writing only? > > > No. Have a look with lsof: > > lsof -p $$ > > in a terminal.
sys.stdin and sys.stdout are distinct, uni-directional io objects. At a lower level though, the only thing stopping you from calling os.write on fd 0 or os.read on fd 1 or 2 is convention. -- https://mail.python.org/mailman/listinfo/python-list
