This command will display the contents of a single file, or concatenate (ie. join end-to-end) the contents of multiple files and display the result.
The most common and simple thing to do with 'cat' is to display the contents of a file on the standard output device, ie. the terminal. We assume that there is a file named 'foo.txt' in the user's home directory.
This command will archive a bunch of your files or directories.
user@box ~$ tar -cf foo.tar foo/
Once the archive is created, we can list the files and directories inside it using the following command.
This command is used to change the current working directory.
user@box ~$ cd /tmp
The above command will change the current working directory to '/tmp'. If you look at the prompt you will see that we were in the user's home directory, indicated by '~', while issuing the command.
user@box /tmp$ cd ..
The above command will take you to the immediate parent of the current working directory. In this example it would take you to '/'.
This command is used to list the contents of a directory, or for seeing detailed information about a particular file.
user@box ~$ ls
The above command will display all the files and sub-directories contained in the current directory, which is right now the user's home directory indicated by '~'.
The next step is to look at the contents of a directory, which is not the current one.
This command is used to rename files and directories; and to move files and directories from one place to another. Moving in this case refers to the act of copying something from one place to another and deleting the older original or source copy.
user@box ~$ mv foo bar
The above command will rename the file or directory named 'foo' in the user's home directory (~ is a an abbreviation for the home directory) to 'bar'.