A detailed description of Linux standard input and output

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 that both the standard output and the standard error output are redirected to the 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)

For example:

[[email protected] ~]# cat tt.txtcat:tt.txt:No such file or Directory[[email protected] ~]# cat Tt.txt &>err.txt[ [email protected] ~]# cat err.txt cat:tt.txt:No such file or Directory[[email protected] ~]#

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A detailed description of Linux standard input and output