Standard input stream output stream error stream

The Linux system treats all the devices as files.

stdin standard input Stream default keyboard

STDOUT standard output stream default display terminal

STDERR standard error stream

Prototypes of scanf and printf

Run test results

Output redirection

Redirect the contents of the a.out output to A.txt

./a.out 1>> a.txt Append the output to the end of the A.txt

./a.out 1> a.txt overwrite the output a.txt

"1" can be omitted

Input redirect

./a.out 1< input.txt//input contents as parameters to be accepted by a.out

Same < coverage

<< not covered

Error stream redirection

PS: Error stream must return error code 1;

Normal state:

If the denominator is 0:

Error is 1 with Echo

Summarize:

1> A.txt represents a standard output stream, 2>b.txt represents a standard error stream, and <c.txt represents a standard input stream

Standard input stream output stream error stream