LINUX-----Pipeline Flow and redirection

1. Pipeline Flow

In Linux | Symbol represents pipeline Flow

Usage: Command1 | Command2

The standard output of the first command will be the standard input for the second command

Example: Cat A.txt | grep "ABC"

2.IO Stream

stdin---Standard input stream with descriptor 0

STDOUT---Standard output stream, descriptor 1

STDERR---Standard error stream, descriptor 2

3. Redirection

Output:

N> Redirect-overlay

Example: Cat A.txt 1>stdout.txt

REDIRECT the output from Cat a.txt to Stdout.txt, not in the terminal display

If stdout.txt exists, then overwrite, not present, create

N>> Redirect--add

Example: Cat A.txt 1>>stdout.txt

REDIRECT the output from Cat a.txt to Stdout.txt, not in the terminal display

If Stdout.txt exists, it is added at the end of the file, does not exist, creates

Description: 1.N represents the descriptor for IO stream in 3, and if n is omitted, the default is the standard output stream

Input:

<

Example:./a.out <a.txt

Set the input of the A.out program to think of A.txt

Reference: http://www.ibm.com/developerworks/cn/linux/l-lpic1-v3-103-4/

LINUX-----Pipeline Flow and redirection