Linux Standard input, output, and error explained

A process structure is constructed with numbered channels (file descriptors) to manage open files. Processes connect to files to reach data content or devices these files represent. Processes are created with default connections for channels 0, 1, and 2, known as standard input, standard output, and standard error. Processes use channels 3 and above to connect to other files.

Number	Channel Name	Description	Default Connection	Usage
0	stdin	Standard input	Keyboard	read only
1	stdout	Standard output	Terminal	write only
2	stderr	Standard error	Terminal	write only
3+	filename	Other files	none	read and/or write

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