Hi!
12-Апр-2004 22:38 [EMAIL PROTECTED] (Bernd Blaauw) wrote to
[EMAIL PROTECTED]:
>> Question: by default, only CON device have bits "stdin" and "stdout"
>> (mask 0x3 in attribute word). What happen if I use "CTTY NUL" - is this
>> equal to plain redirecting to NUL or shell sets stdin+stdout bits in
>> attribute word (INT 21/4401, as I understand)?
BB> input is also set to NUL device.
_How_ it set? Why I ask: I already talks how Eugeny Roshal differs CON
and NUL devices (by stdin/stdout bits set for CON). If CTTY NUL sets these
bits (also) for NUL, then now we can't differ NUL and CON.
Why this is important. Imagine, some programs detects redirection and
asks prompt for next screen only if it "not redirected" (it. its output
linked to device with stdin/stdout bits set). Now, if we redirect streams by
CTTY NUL _and_ CTTY sets stdin/stdout for NUL devices, then discussed
program will think, that NUL is CON and will try to wait answer from NUL
device. Infinity loop.
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