September 15, 2019
What are the differences between a
It turns out it’s both a lot and a little.
.ziprepresents a compressed archive of the file(s). It uses a LZ77 algorithm and was one of the first compression techniques to market.1
.taris a way to stream data and is actually not compressed. Though it can be easily GZipped (which is when you see the
.gz) or passed through a different compression algorithm (
.raris a Windows specific compression. Files can be extracted on MacOS using the Homebrew formula
Sylvain Leroux wrote an informative article on the differences between tar, zip, and gz which I found very useful.2
As far as I can tell, the differences are largely the method of compression with associated trade-offs there. This Quora answer was helpful in spelling out some of the differences.3
Gzip is one of the more popular methods for compression in the Unix ecosystem as the Zip protocol was hindered by copyright limitations early on.
To create a gzip from the terminal, use the
tar command. For example, to create gzip of a directory’s
$ tar -cvzf <name-of-tar>.tar.gz /path/to/directory/*.jpg
The wildcard (
*) means that anything with an extension of
.jpg in the directory will be compressed.
This example uses several flags in quick succession. Their definitions from the manual are:
-c Create a new archive containing the specified items. The long option form is --create. -v, --verbose Produce verbose output. In create and extract modes, tar will list each file name as it is read from or written to the archive. In list mode, tar will produce output similar to that of ls(1). An additional -v option will also provide ls-like details in create and extract mode. -z, --gunzip, --gzip (c mode only) Compress the resulting archive with gzip(1). In extract or list modes, this option is ignored. Note that, unlike other tar implementations, this implementation recognizes gzip compression automatically when reading archives. -f file, --file file Read the archive from or write the archive to the specified file. The filename can be - for standard input or standard output. The default varies by system; on FreeBSD, the default is /dev/sa0; on Linux, the default is /dev/st0.
If we did not include the
-z flag, we would not have compressed the files, but still would have created the
.tar. In that way, we’d be able to consolidate a group of files to easily identify them, but would have saved minimally on storage as they would not have been compressed.
$ zip <name-of-archive>.zip /path/to/directory/* $ zip <directory-archive>.zip /path/to/directory
The difference between the two examples is that the first will archive and compress all of the files within the directory, without archiving the directory (and so the name of the directory will not persist). On the other hand, in the latter case, when you extract the directory archive, it will contain a directory within it.
While other options exist, if you’re so inclined so as to want a
.rar archive, you can do it through the use of the
.rar cask formula on Homebrew.
$ brew cask install rar $ rar a <file-to-archive>
To see the options, access the help menu with the
$ rar -? RAR 5.71 Copyright (c) 1993-2019 Alexander Roshal 28 Apr 2019 Trial version Type 'rar -?' for help Usage: rar <command> -<switch 1> -<switch N> <archive> <files...> <@listfiles...> <path_to_extract\> <Commands> a Add files to archive c Add archive comment ch Change archive parameters cw Write archive comment to file d Delete files from archive e Extract files without archived paths f Freshen files in archive …
$ gunzip <filename>.gz $ gzip -d <filename>.gz
These are synonymous as the
gunzip application is the same as the
gzip with the
-d flag where
-d is for decompression.
$ unzip <filename>.zip
.rar is a Windows format, it is possible to extract it on a Mac using the
unrar Homebrew formula.4
$ brew install unrar $ unrar <filename>.rar
The good news is that while I focused on the MacOS variant of a Unix system, most of these commands should work on a Linux OS. The purpose of this post was not to say which is better — there are plenty of posts about that. Rather it was to ensure a basic understanding of the differences (the differences are not that big) and a working understanding one how to use them.
Thanks for reading! My name's Stephen Weiss. I live in Chicago with my wife, Kate, and dog, Finn.
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