The path of Linux learning

Chapter III pipeline character, redirection and environment variables

　　The pipe command , "|", is used to treat the standard output of the previous command as a standard input to the latter command,

Format: "Command a| command B"

　　input and output redirection ,

Standard input, STDIN, file descriptor 0, default input from keyboard, 0 indicates output from other places or commands

Standard output, STDOUT, file descriptor 1, default output to screen, 1 indicates file

Error output, STDERR, file descriptor 2, default output to screen, 2 indicates file

The following is the case for output redirection:

Symbolic effect

Commands > Files redirect standard output to a file (clears the data from the original file)

Command 2> file redirects the error output to a file (clears the data from the original file)

Commands >> files redirect standard output to a file (appended to the original content)

The command 2>> file redirects the error output to a file (appended to the original content)

Command >> file 2$1 writes standard output and error output to a file (appended to the original content)

The following is the case for input redirection:

Command < file as standard input to the command

The command << delimiter reads the standard input into, until the meeting demarcation characters stops

Command < file 1> File 2 set file 1 as the standard input for the command and output the standard to file 2

The path of Linux learning