True and false (commands)

True is a computer program in Unix-like systems and part of the POSIX standard. The program returns the value 0, which is interpreted true of the Unix shell as a truth value. It is used in shell scripts to control structures. The following example is an infinite loop, the Hello World output until the process is canceled by the user:

While true do    echo Hello World done In modern shells is true a built-in command, which is interpreted by the shell itself and running so quickly. Usually located at / bin / true nevertheless a separate program that has this functionality.