File are collection of data items stored on disk. Or it's device which can store the information, data, music (mp3), picture, movie, sound, book etc. In fact what ever you store in computer it must be inform of file. Files are always associated with devices like hard disk ,floppy disk etc. File is the last object in your file system tree.
Filenames may contain any character except / (root directory), which is reserved as the separator between files and directories in a pathname. You cannot use the null character.
- Filenames that begin with a period character are hidden. This only means that ls will not list them unless you say ls -a. When your account was created, several hidden files were placed in your home directory to configure things for your account. Later on we will take a closer look at some of those files to see how you can customize your environment. In addition, some applications place their configuration and settings files in your home directory as hidden files.
- Filenames and commands in Linux, as in Unix, are case sensitive. The filenames File1 and file1 refer to different files.
- Linux has no concept of a “file extension” like some other operating systems. You may name files any way you like. The contents and/or purpose of a file is determined by other means. Although Unix-like operating systems don’t use file extensions to determine the contents/purpose of files, some application programs do.
Though Linux supports long filenames that may contain embedded spaces and punctuation characters, limit the punctuation characters in the names of files you create to period, dash (hyphen), and underscore.
Most importantly, do not embed spaces in filenames. Embedding spaces in filenames will make many command line tasks more difficult. If you want to represent spaces between words in a filename, use underscore characters. You will thank yourself later.
Like the root (/) character, you should also avoid using the following characters from appearing in file names as they are reserved characters by Linux / Unix
If you are using an older version of Linux or UNIX, the maximum limit for a filename is restricted to only 14 Characters. However, Most modern Linux and UNIX limit filename to 255 characters (255 bytes).