input/output
<programming, operating system> (I/O) Communication between a computer
and its users, its storage devices, other computers (via a network) or the
outside world. The devices the computer uses to do this are called
"peripherals". What actually counts as I/O depends on what level of detail you
are considering, e.g. communication between processors would not be considered
I/O when considering a multiprocessor as a single system.
Important aspects of I/O are throughput, latency, and whether the communications
is synchronous or asynchronous (using some kind of buffer).
(2003-12-04)
Nearby terms:
Input « input « input device « input/output »
input/output redirection » inquiry/response system »
INRIA
input/output redirection
<operating system> In Unix, to send ouput from a process to different
file or device or to another process via a pipe, or to have a process read its
input from a different file, device or pipe. Some other operating systems have
similar facilities.
To redirect input to come from a file instead of the keyboard, use "<":
myprog < myfile
Similarly to redirect output to a file instead of the screen:
ls > filelist
A pipe redirects the output of one process directly into the input of
another
who | wc -l
A common misuse by beginners is
cat myfile | myprog
Which is more or less equivalent to "myprog < myfile" except that it
introduces an extra unnecessary cat process and
buffer space for the pipe. Even the "<" is
unnecessary with many standard Unix commands since
they accept input file names as command line
arguments anyway.
Unix's concept of standard input/output and I/O redirection make it easy to
combine simple processes in powerful ways and to use the same commands for
different purposes.
(1998-04-24)
Nearby terms:
input « input device « input/output «
input/output redirection » inquiry/response
system » INRIA » insanely great
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