Linux standard input and output

RPM: Linux standard input and output

A file descriptor is a simple positive integer that identifies each file and socket that is opened by the process.
The first three file descriptors (0,1,2) correspond to standard input (stdin), standard output (stdout), and standard error (STDERR), respectively

0 indicates standard input
1 indicates standard output
2 indicates standard error output

> default to standard output redirect, same as 1>

2>&1 means redirecting the standard error output to the standard output.

&>file means to redirect both the standard output and the standard error output to file

2>&1 > file directs error to standard output (at this point the standard output is the terminal, so output to the terminal), the standard output is positioned to the file

> file 2>&1 to the standard output to the files, error output to the standard output (at this point the standard output point to the file, so output to a file)

Difference Reference: http://blog.csdn.net/ajaxuser/article/details/8850543

Linux standard input and output