Hello,
I tried to cat < /dev/mytty/ttyS3, but cat shows nothing. I attached here strace
cat < /dev/mytty/ttyS3 and cat < hello. Hello is just a file. As you can see the
result of strace cat is identical, but in tty case I can't see nothing. Why does cat write nothing at my console?
Thank you,
------------------------------------------------------------------------------------
root@test:/home# strace cat < hello
?c?c?c?c?c?c?c?c?c?c?c?c..
munmap(0x40017000, 5664) = 0
getuid32() = 0
getgid32() = 0
setgid32(0) = 0
setuid32(0) = 0
read(0, "Hello World!", 8192) = 12
write(1, "Hello World!", 12Hello World!) = 12
read(0, "", 8192) = 0
io_submit(0, 0x40200164, 0 <unfinished ... exit status 0>
Process 1520 detached
root@test:/home# strace cat < /dev/mytty/ttyS3
?c?c?c?c?c?c?c?c?c?c?c?c?c.
getuid32() = 0
getgid32() = 0
setgid32(0) = 0
setuid32(0) = 0
read(0, "\376\377\377f\377\330\0000", 8192) = 8
write(1, "\376\377\377f\377\330\0000", 8?? f0) = 8
read(0, "", 8192) = 0
io_submit(0, 0x40200164, 0 <unfinished ... exit status 0>
Process 1522 detached
root@test:/home#
> result of strace cat is identical, but in tty case I can't see nothing. Why does cat write nothing at my console?
>
> Thank you,
>
> ------------------------------------------------------------------------------------
>
> root@test:/home# strace cat < hello
> │c│c│c│c│c│c│c│c│c│c│c│c..
> munmap(0x40017000, 5664) = 0
> getuid32() = 0
> getgid32() = 0
> setgid32(0) = 0
> setuid32(0) = 0
> read(0, "Hello World!", 8192) = 12
> write(1, "Hello World!", 12Hello World!) = 12
you read "Hello World!" and you write "Hello World!" to the console
> read(0, "\376\377\377f\377\330\0000", 8192) = 8
> write(1, "\376\377\377f\377\330\0000", 8│║ f0) = 8
and here you read garbage from the input, so you write garbage out,
which probably confuses the heck out of your terminal for not being
correct UTF-8