Linux pipelines and redirection

Linux pipelines and redirection data streams classification command line shell data streams have the following definition name description number default STDIN standard input 0 keyboard STDOUT standard output 1 terminal STDERR standard error 2 terminal command through STDIN receive data, through... linux pipelines and redirection data streams classification command line shell data streams have the following definition name description number default STDIN standard input 0 keyboard STDOUT standard output 1 terminal STDERR standard error 2 terminal command through STDIN receive data, use STDOUT to output results or STDERR to output error pipelines and redirection we can control data stream classification keyword function example redirection> redirect STDOUT to file (overwrite) echo "test"> outfile> redirect STDOUT to a file (append) echo "test"> outfile2> redirect STDERR to a file (overwrite) ls okkkk 2> errfile2> & l redirect STDERR to the file where STDIN is located ls OK> file 2> & 1 pipeline | use the STDOUT of the first command as the STDIN ls-of the second command- l | grep "file_to_find" redirection to the device/dev/null will be discarded