Filename with dot in front

Question

If there is a file and the filename starts with a dot, does that mean you created the file and you are hiding stuff in it, or can the files get created on their own without you creating the filename?

Answer 1

The only thing "special" about a file or directory with a leading dot in its name, such as .myfile, is that it will not show up in the output of ls by default. It will also not be matched by a file name globbing pattern that does not explicitly match filenames starting with a dot.

Assuming an initially empty directory:

$ touch .myfile    # this creates an empty hidden file
$ ls               # this will output nothing
$ echo *           # this will echo a *
*

These files are usually called "hidden". However, they are only hidden from ls and filename globbing patterns, and not hidden in the sense of "being a secret", or being malicious, or being undetectable or being unreadable by others (that depends on the file's permission and the permission of its parent folder(s)).

Anyone can create hidden files; it's just a matter of putting a dot at the start of the name. The fact that a file is hidden says nothing about how it was created (explicitly by a user or by running some program). For example, some applications create directories with hidden names (for storing configurations and cache files, etc.), and others create hidden files.

For example,

• The bash shell will often create .bash_history in your home directory, containing the commands that you have typed at the command prompt (so that you can easily recall them in a later session without having to retype them). Upon starting up, the shell will also use .bash_profile and .bashrc in your home directory. If these files exist, they were likely copied to your account when it was created.

• If you use SSH, you will likely have a hidden directory called .ssh in your home directory. This directory contains public and private SSH keys and may include some configuration files. This directory should not be accessible by others. It is unlikely that you created this directory manually.

• Many desktop utilities will store their configuration files somewhere under .config in your home directory and cache files under .cache. Again, it is unlikely that you created these directories manually.

Configuration files in users' home directories (and elsewhere) are often hidden in this way so that they don't clutter the output of ls.

To view all files in a directory, including hidden files, use the -a or -A option with ls (using -A will not show the . and .. names present in any Unix directory).

$ ls -a
.       ..      .myfile

$ ls -A
.myfile

In the bash shell, * and other shell globbing patterns will not match hidden names. To get them to do that, enable the dotglob shell option with shopt -s dotglob.

$ echo *
*

$ shopt -s dotglob
$ echo *            # the * now matches a filename, so it is replaced by it
.myfile