Using Zip files _________________________________________________________________________ Zip files are a special sort of file because they are an archive of other files and folders – all the information in the files and folders is copied into one single file, and it is compressed so that it takes up less space. Zip files are commonly used for two purposes: 1. To store archives of information for long-term storage: for example, old student data which is not likely to be needed, but has to be kept for whatever reason. 2. To bundle a set of files and folders into one single, small file so that it can be easily sent across the internet. Often when you download software from the internet, you only need to download one file, because all the software’s files are compressed into one zip archive. Getting files and folders back out of a zip archive is called extracting. _________________________________________________________________________ Creating zip files To create a zip file you will need a file compression program such as WinZip or PowerArchiver. Whichever you use, the process will probably be very similar to that described here (based on PowerArchiver). Start your program and then choose the “New” option to create a new archive. A file selector box will appear for you to choose where to create your archive, and what to call it. Make sure you choose an appropriate location (folder) to put the file, and give it a name which is appropriate to the contents you’re going to put in the archive. The next step is to choose the files and folders you wish to include in the archive. A file selection box like the following should appear – if not choose the “Add” option on your software: You can use this just as you would use the file selector in any other application – pick the file you wish to add, and then press [Enter] or select the “Add” button. You will usually be interested in adding multiple files to your archive, so remember that you can select more than one file/folder at once by holding down the [Control] key while clicking on each file, and then choose “Add” once you have selected all of them. There are a number of options on this file-selector window, however, and some of these can be important: “Save Relative folder info” / “Save Full folder info” When you add files to a zip archive – for example, if I added my folder named “two” shown in the above picture – they can be stored in three ways: 1. Without any folder information. All the files inside the “two” folder will be put into the archive, and then when they are extracted later there will be no information about where the files should go – no record is kept of the “two” folder. 2. With relative folder information. All the files inside the “two” folder will be put into the archive, but this time the information about the “two” folder will also be stored. When the archive is extracted, the files will be put into a “two” folder. 3. With full folder information. In the above screenshot the full path to my desired folder is R:\webct\test\two , and if I used this third option then not only would the archive record that the files were in the “two” folder, but also that the “two” folder was in the “test” folder, and that the “test” folder was in the “webct” folder. Extracting a file from the archive would cause it to be put in the subfolders “webct\test\two” (these folders will be created anew if they don’t exist). Which of these options you choose depends on the purpose of the archive you are creating. Often the second option, to save relative folder information, is the preferred option. Compression Most archiving programs allow you to select how much compression to use. With no compression or low compression, then the zip file will not be as small as it could be. Selecting high or full compression will mean that the file is as small as possible – it may take a few seconds extra for the program to achieve this compression. Set Password If you would like this zip file to be a secure archive (so that a password is needed before it can be accessed, extracted, or modified) then this option is available. Do not use this unless you’re sure the password can be made available for people to access the file in future! _________________________________________________________________________ Extracting a zip archive When a zip file has been created, it is just like any other file – you can copy it, move it, delete it, email it as an attachment, and so on. If you opt to open the file (for example, by double-clicking on it) then your archiving program will start, and you will be able to extract some or all of the files from the archive. You can also get to this point by starting your archiving program then selecting “Open”, and then choosing the zip file with the file selector. You will then be shown the files and folders which are contained within the archive: Notice that the “Path” column, on the right-hand side, shows the folder information which has been stored along with each file. To extract files from the archive onto your computer, select them in the window and then choose the “Extract” option. A file selector will pop up for you to choose where to place the extracted files. Again there are various options. The option here called “Use Folder Name” tells the program whether or not to pay attention to the path information stored alongside each file in the archive. You can also choose whether you want to extract only the files you have selected, all the files in the archive, or a set whose names you type in.