Because UNIX uses special characters for special purposes, it is best to use only letters, digits, periods, and underscores in file names. Files are created by various UNIX commands. You can save your mail messages in files. You can also create text files with an editor. Files are located in directories .
Directories can contain other directories, which are called subdirectories .
The directory containing a subdirectory is known as the parent of the subdirectory. Each account has a main directory known as its home directory . The ls command lists the names of files in the current directory. The mkdir command is used to create directories. Basic file manipulation commands include mv for moving or renaming files, cp for copying files, lpr for printing files, and rm for removing files.