Listing Hidden Files (ls -a)
Some files are not listed by the ls command. These files have names that begin with the character . (called “dot”), such as .cshrc, .login and .profile. Use the ls -a command to list these dot files:
$ ls -a
Notice that the files beginning with . are listed before the other files. The file . is the reference for the current directory, and the file .. is the reference for the parent directory.
In general, system utilities use files that begin with . and the user cannot modify these files. Some exceptions to this rule do exist.