7-Zip, Tar

It is possible to use the "tar" command to create and expand 7-Zip (7z) files. On platforms like macOS that have tar, no separate 7-Zip program is needed.

With the "a" flag, we tell tar to compress an archive based on the specified file name. So if we use a ".7z" extension, 7-Zip is used.

Compress

To begin we need to compress an archive. Suppose we are in a folder with a directory named "work" that we want to compress with 7-Zip.

Part 1 We specify "a" for auto mode, and then "c" to indicate we want to compress, and the "f" means we are specifying the target file.

Part 2 To specify more powerful compression with 7-Zip, use the options flag and specify the 7-Zip compression level. The value 9 is the maximum.

' Part 1: for default compression with tar and 7-zip:
tar -acf archive.tar.7z work

' Part 2: for optimal compression:
tar --options 7zip:compression-level=9 -acf archive.tar.7z work

Extract

On macOS, Windows and Linux it is usually possible to expand the archive by clicking on it. But we can use tar to do this directly, which is sometimes desired.

Tip The "x" flag means expand, and the "f" means we are specifying the file name to expand. Tar automatically detects the format when expanding.

Further We create a temp folder, and then expand into it with the "C" flag (this flag is not always needed).

' To decompress 7z file with tar:

mkdir temp
tar -xf archive.tar.7z -C temp

Notes, commands

When using tar, it is important to specify "c" or "x" to compress or expand. And "a" means tar can detect the compression format from the file name.

Finally The "f" flag is used on most every command line, as it means we are specifying an archive file (to read or write).

' Some tar flags:

a - auto compress
c - create new
x - expand existing archive
f - file to use (can read from archive or write to file)

The 7-Zip format is both efficient and widely-used. It can compress better than many other formats, and even programs like tar can handle it.

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This page was last updated on Mar 7, 2025 (image).

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