2/16/11
11:13 am

MacMost Now 517: Simple File Compression In OS X

You can use Mac OS X's built-in file compression command to create a ZIP archive of a single file or group of files. This comes in handy if you need to send files to someone else or simply want to archive an old project.

Video Transcript
Hi, this is Gary with MacMost Now. On today's episode, let's look at compressing files in OS 10.
So OS 10 has a built in way to create a compressed archive of a single file or groups of files. It compresses it using the zip file format, and .zip file extension. Let's take a look.
So here I have a bunch of files in my documents folder. Now let's say I want to compress one of them. Let's take this Info.rtf text file. We see it's 127k. Maybe I want to e-mail it to somebody, so I want to compress it so it's a little smaller. I can right-click or control-click on the file, and one of the options I get is Compress. So I will select that and very quickly I'll have a Info.rtf.zip file, and I can see it's only 37k compared to the 127k of the original.
The zip format is a standard format, so you can zip up some files and send it to people even if they don't have Macs, if they're on Windows or Linux.
To decompress this file, all you have to do is double-click it in the Finder, and it will decompress it, and you can see here, since there was a name conflict, it put a space 2 after it, and you can see I now have a copy of the original.
Now, the compression isn't always that dramatic. For instance, here's a jpg image. I'm going to compress that, and you can see the file I get is only a little smaller than the original. Now let me try it with a video file. Here's an mpg compressed video file. I'm going to compress that. Ah, see, here I get a modest amount of compression.
So the reason it didn't work so great for the jpg and the video file is those formats already contain compressed data. mpg files and jpg, they're both kinds of compression, so you're compressing something that's already compressed and you're only going to get a little bit more savings out of it, whereas text file isn't compressed at all, so you get a lot of savings out of compressing that.
Now you can also compress multiple files at the same time, so for instance, let me select this rtf file and also the jpg. I'm going to do that by holding the command key key down and selecting both of them, and then control-click just one of the two. You can see both are still selected there. And you can see it'll say "Compress 2 Items". And when I do that, it doesn't know exactly what it should name it, so it names it Archive, and you get Archive.zip, and it's a zip file with both of these in there. So I can compress a whole bunch of files into a single zipped archive with this method. Of course you can also compress a whole folder full of documents. Just control-click on the folder, compress, and then you get a compressed copy of that entire folder.
Now there are a lot of reasons why you may want to compress files. One is if you're trying to send something to somebody, say via e-mail, or upload it to a server, and you find a compressed version is much smaller, it's going to make it easier for you to upload and for them to download. Also, sometimes it's easier to gather a lot of files together to a single compressed zip file rather than send somebody a whole bunch of different files. Also, if you're completely done with a project, say it's a folder filled with hundreds of files, you may want to compress it. This makes it a single file on your drive, may save a little bit of space, kind of gets it out of the way, and also it removes it from your searches, so if you're searching for something, you're not going to get all these files from a project that you know you're not going to need anymore.
Now of course there are many programs you can get that allow you to have more control over the compression. They allow you to choose different formats and different settings for those formats. But for basic needs, using the simple built-in OS 10 compression can be very useful.
So until next time, this is Gary with MacMost Now.

Comments: 3 Responses to “MacMost Now 517: Simple File Compression In OS X”

    Vic
    2/16/11 @ 1:41 pm

    Hey Gary! I wanted to know if there’s some way to compress one big file, let’s say a video, into little zips so I can send it to someone through email. I got the keka.app but I’m not so sure how to use it…
    thanks!

      2/16/11 @ 2:00 pm

      I’m not familiar with Keka. It has been years since I had to do something like that. I’d imagine there are some programs out there that would do it for you. But why not just use DropBox or iDisk or something like that. If the file is so big that you need to break it into multiple zips to send it, then it is probably something you shouldn’t be sending via email. Using a shared cloud space is much better.

    Vic
    2/16/11 @ 2:13 pm

    Yeah, I think I’ll use dropbox, thanks!

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