3.3.3.1. Using shell features

In the example on moving files we already saw how the shell can manipulate multiple files at once. In that example, the shell finds out automatically what the user means by the requirements between the square braces "[" and "]". The shell can substitute ranges of numbers and upper or lower case characters alike. It also substitutes as many characters as you want with an asterisk, and only one character with a question mark.

All sorts of substitutions can be used simultaneously; the shell is very logical about it. The Bash shell, for instance, has no problem with expressions like ls dirname/*/*/*[2-3].

In other shells, the asterisk is commonly used to minimize the efforts of typing: people would enter cd dir* instead of cd directory. In Bash however, this is not necessary because the GNU shell has a feature called file name completion. It means that you can type the first few characters of a command (anywhere) or a file (in the current directory) and if no confusion is possible, the shell will find out what you mean. For example in a directory containing many files, you can check if there are any files beginning with the letter A just by typing ls A and pressing the Tab key twice, rather than pressing Enter. If there is only one file starting with "A", this file will be shown as the argument to ls (or any shell command, for that matter) immediately.