What is TGZ?

What is TGZ?

TGZ, also written as .tar.gz, is a compound format in which files are first combined into a single tar archive and that archive is then compressed with gzip. The result is one file that preserves Unix file structure and metadata while reducing size.

The two stages are separate: tar handles bundling and metadata such as permissions and timestamps, while gzip applies DEFLATE compression to the whole tarball. The .tgz extension is simply a shorthand for .tar.gz, and the file is decompressed by gunzip and then unpacked by tar.

How TGZ Works

A .tgz file is simply a .tar.gz under a shorter name, a convenience spelling for systems or people who prefer a single three-letter extension. It is the product of two separate steps stacked together: first tar bundles a set of files and directories into one uncompressed archive, then gzip compresses that whole archive into a single stream. Understanding it means understanding that pairing.

The tar stage handles packaging. It walks the files you give it and writes each one preceded by a header block recording its name, size, permissions, owner, and timestamp, preserving the full Unix metadata so the tree can be restored exactly. At this point nothing is smaller; tar only concatenates.

The gzip stage then handles compression, running the entire tar stream through the DEFLATE algorithm (LZ77 dictionary matching plus Huffman coding) to remove redundancy. Because gzip sees the whole concatenated archive at once, it can exploit similarities between the bundled files, which is why a .tgz of many small related files often compresses better than compressing each one separately.

One practical consequence of this order matters: to read a single file you must first gunzip the stream and then scan the tar for the entry, since tar has no index and gzip must be decoded from the start. In everyday use a single command such as tar xzf archive.tgz does the ungzip and untar together, hiding the two-step nature entirely.

History and Standardization

The .tgz spelling arose for a practical reason. Older filesystems, especially DOS and early Windows with their eight-plus-three naming limits, could not comfortably hold a compound extension like .tar.gz, so the contraction .tgz became the portable way to name the same thing.

Both underlying formats are long-standing open standards: tar's layout is defined by POSIX (the ustar and pax formats), and gzip is specified in RFC 1952 with its DEFLATE core in RFC 1951. Because .tgz is just those two well-defined pieces combined, every tar and gzip implementation reads it, and no separate specification is needed.

The pairing became the default distribution format across the Unix world for source code, backups, and general file transfer. It remains extremely common today, and any modern archive utility on any platform recognises both the .tar.gz and .tgz spellings interchangeably.

TGZ Compared to tar.bz2, tar.xz, and ZIP

Compared to the other tar pairings, .tgz is the fast, universal option. Swapping gzip for bzip2 (.tar.bz2) or XZ (.tar.xz) yields a smaller file but slower compression and, for bzip2, slower decompression. .tgz wins when speed and maximum compatibility matter more than the last few percent of size.

Against ZIP, the difference is the same as tar versus ZIP generally. ZIP compresses each file individually and keeps a central index for fast single-file access, while a .tgz compresses the whole bundle as one stream. That gives .tgz better cross-file compression and full preservation of Unix permissions, at the cost of not being able to pull out one file without processing the archive up to it.

Because a .tgz is nothing more than tar plus gzip, it inherits both of their traits: tar's faithful metadata handling and streaming design, and gzip's speed and universal support. That combination is why it stayed the everyday default for shipping and archiving files on Unix-like systems for decades.

MKV Technical Specifications

TGZ vs Other Archive Formats

TGZ compresses an entire TAR stream as a whole, so unlike ZIP it cannot extract a single file without decompressing the archive.

Advantages & Disadvantages

Common Use Cases

TGZ is a default choice for packaging and moving files in Unix-like environments.