College of Engineering & CS
Wright State University
Dayton,
Ohio 45435-0001
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CEG 333: Introduction to UnixPrabhaker MatetiStandard Files, Redirection and Pipes |
"stdout" and "stdin" are the normal text input and output of commands, i.e. what shows up in the terminal. C++ programmers can think of them as like "cout" and "cin". There is also a "stderr" for the output of error messages.
The shell usually refers to them by number: stdin == 0, stdout == 1, and stderr == 2.
| Command | Summary | Examples | |
> FILE |
Redirect stdout. | c1 > FILE |
Overwrite the contents of a file with the stdout of "c1". |
c1 >> FILE |
Append the stdout of "c1" to a file. | ||
< FILE |
Redirect stdin. | c1 < FILE |
Use the contents of a file as the stdin for "c1". |
c1 | c2 |
Pipe the stdout of "c1" to the stdin of "c2". | ps aux | grep Emacs |
Shows the PIDs of all running Emacs processes. |