A tiny application which demonstrates how to use the GNU Readline library. This application interactively allows users to manipulate files and their modes. Then, if there is anything left, add it to the history list and execute it. Return a NULL pointer if NAME isn't a command name. We want to try to complete on command names if this is the first word in the line, or on filenames if not.
TEXT is the word to complete.
Return the array of matches, or NULL if there aren't any. If this word is at the start of the line, then it is a command to complete. Otherwise it is the name of a file in the current directory. This includes saving the length of TEXT for efficiency, and initializing the index variable to 0. The user wishes to quit using this program.