Which command is used for standard input redirection in Linux?

The command used for standard input redirection in Linux is represented by "COMMAND." In the context of Linux, redirection allows users to control where the output of a command is sent or where the input is sourced from. Standard input redirection typically involves using operators such as <, which directs the command to take its input from a file instead of the default input source, the terminal.

The concept of standard input redirection is a fundamental part of Unix-like operating systems, enabling users to pipe data between commands or to utilize files as inputs to commands. For example, if you have a command that expects input (like a script or a utility), you can redirect a file containing the necessary input into that command using the syntax COMMAND < inputfile.

Other options like "echo," "cat," and "ls" are specific commands that perform certain functions but are not inherently related to standard input redirection. While they can work in conjunction with input redirection—such as using cat file.txt to display the contents of a file—it is the notion of "COMMAND" that encompasses any executable command that can utilize input redirection.