Unix Basics
Intro
UNIX is an operating system which was first developed in the 1960s, and has been under constant development. Originally UNIX was a command-line based operating system, like DOS.
Terminal
Each UNIX desktop comes with a Terminal program similar to the Command Prompt in Microsoft Windows operating system.
Using the Terminal - Working with directories
Listing files and directories
ls list the content (files and folders) of the current working directory
ls –a list all the files and directories including hidden files in the current working directory
Making Directories
mkdir myFolder create a new empty directory into the current working directory named myFolder
Changing to a different directory
cd myFolder change the current working directory to the specified directory which resides in the current working directory (in this case)
cd changes the current working directory to the home directory
The directories . and ..
cd . the current directory (does not change directory)
cd .. go to the parent directory
Pathnames
pwd print the full path of the current working directory
Using the Terminal - Working with files
Creating Files
Many people create files using a text editor, but you can use the command cat to create files without learning a text editor. To create a practice file (named firstfile) and enter one line of text in it, type the following at the % prompt:
cat > firstfile (Press the Enter/Return key.)
This is just a test.(Press the Enter/Return key.)
Stop file entry by typing Control-d on a line by itself. (Hold down the Control key and type d.) On your screen you will see:
% cat > firstfile
This is just a test.
^D
One way to examine the contents of the file you’ve just created is to enter this at the % prompt:
cat firstfile
Copying a File
To make a duplicate copy of a file, use the command cp. For example, to create an exact copy of the file called firstfile, you would type:
cp firstfile secondfile
The result is two files with different names, each containing the same information. The cp command works by overwriting information. If you create a different file called thirdfile and then type the following command:
cp thirdfile firstfile
you will find that the original contents of firstfile are gone, replaced by the contents of thirdfile.
Renaming a File
Unix does not have a command specifically for renaming files. Instead, the mv command is used both to change the name of a file and to move a file into a different directory.
To change the name of a file, use the following command format (where thirdfile and file3 are sample file names):
mv thirdfile file3
The result of this command is that there is no longer a file called thirdfile, but a new file called file3 contains what was previously in thirdfile.
Like cp, the mv command also overwrites existing files. For example, if you have two files, fourthfile and secondfile, and you type the command
mv fourthfile secondfile
mv will remove the original contents of secondfile and replace them with the contents of fourthfile. The effect is that fourthfile is renamed secondfile, but in the process secondfile is deleted.
