7Z archiving format was created for
popular modern file archiver application written by Igor
Pavlov, and released as freeware and Open Source software. 7-Zip
(often incorrectly shortened in 7zip) was developed for
Microsoft Windows platforms, and ported by p7zip (POSIX-7Zip) project
is capable of very high compression ratio through powerful
algorithms (LZMA/LZMA2, PPMd, BZip2, optionally optimized
cost of more
memory and CPU
intensive compression process
- that however can take benefit
parallel computing on modern multicore CPUs.
On average test cases 7Z
format improves compression ratio 30-70% better over classic ZIP format, and 6-7% better than RAR files (WinRar's
native format, proprietary). 7Z compression compares favourably also
with new WinZip's ZIPX format
in most cases.
7Z format also provides native UTF-8 support for filenames,
encryption, and volume spanning.
When is 7Z format
in brief, .7z is a good choice anytime
it is important to attain a superior compression ratio, and it is
welcome the support for strong encyption to keep archived data private.
XZ extension identify a pure compression
format (compresses a single file, without offering option of archiving
multiple input file into a single output .xz file), it is based on
family, providing the usual 7z-like compression ratio (similar or
higher compared to RAR), recently often used on TAR files.
Average. Computing intensive compression algorithms are balanced by
efficient parallel programming implementation.
Very good. Comparable, often better than RAR compression, but inferior
to state of art PAQ compressor.
Good. Native support for AES encryption and UTF-8 encoding. Lacks
recovery records option
available for RAR format.
PeaZip offers full read / write support for 7Z archives and XZ files,
through the Open Source components from 7-Zip and p7zip projects
under LGPL license, as PeaZip) to offer the same GUI
browse, and extract 7Z archives under Windows
and Linux operating systems.
The software can also manage password protected 7z archives (encrypt
decrypt), and convert files to / from 7z format.
As alternative, 7-Zip (on MS Windows systems) and p7zip (on Linux/BSD),
both free and Open Source tools, are recommended for working with 7z
Compress to 7Z format
Use one of the following procedures to add
folders to a new or
into an existing .7z file
From main archive creation interface it is possible to apply encryption (recipient will need
to enter a password to read/extract the archive), and to split file - set creation
of multiple volumes declaring
the maximum output size
(spanned archive), in order to keep the output size
below mandatory limits (e.g. upload or mail attachment size).
From "Advanced" tab, you can
fine-tune compression settings: faster or higher compression level,
algorithm, solid compression
block size, compress open files, create self extracting archive (SFX)
will not need an archive
program to extract the data...
From "Console" and "Schedule" tab, the compression / backup task
created in the GUI can be saved as command line script and (on Microsoft
operating system) scheduled for execution at fixed time intervals
(hour, day of the week or of the month) - same apply for extraction /
restore tasks, as the same tabs are featured in archive extraction
Update existing 7Z archive
To update existing archive,
adding files and folders, proceed as shown above for archive creation,
but select an existing
archive as output and chose add (always
replace files in archive) or update (overwrite
only older files in archive) "archive function" in
Easiest way to edit an existing archive is opening it in PeaZip and
dragging files/folders to it, which will automatically activate update
mode - can be changed into add mode in advanced tab.
To remove (delete) data from
the archive, select items and press cancel or "Delete from archive"
button. Deleted items will not be recoverable from recycle bin.
Entries in the context menu on the right of delete button allows to
delete the entire archive in different supported ways (recycle, quick
delete, overwrite with zeroes, secure
delete shredding data to make the archive not recoverable)
Convert 7Z files
procedure using Convert button
extracts and then re-pack input archive files into any write-supported
format (7z, arc, pea, tar, zip...), optionally keeping or discarding
This makes possible to convert any type
supported for reading (e.g. ACE, CAB, RAR, TAR, ZIP...) into a new 7Z
file (either one for each individual input archive, or consolidating
all input items in a single output archive), as well as to convert
existing 7Z file into another write-supported format.
Open and extract 7Z file
Use one of the procedures described below to
(browse and search
inside the archive) and/or decompress
.7Z archives or .XZ files
To extract a spanned (split) 7Z file, save all the parts in the same
directory, then open as usual the first volume of the archive, which
has .7Z.001 extension - subsequent volumes have
progressively numbered file extensions (002, 003 etc).
From the system
archive's content, open it in
PeaZip with double click (if file extension is associated with the
application), or using system context menu "Open as archive" entry,
will attempt to read any user provided file type regardless file type
associations - this option is also available in PeaZip's context menu
Use context menu entry "Extract..."
extraction screen GUI where to set
output path and other options
Select one or more archives and use
entry Extract here or Extract
here (to new folder) for quick extraction with no further
Extract button shows full featured
extraction screen providing access to all options (password, set output
path, open output path after extraction, keep or delete original
archives, etc) and can send to extraction selected items only
Extract all to... button activate a
procedure only asking for output path
Simply drag & drop desired objects
application to the system
Doubleclick on an archived file to
mode, i.e. to inspect its content before considering the need for real
Manage encrypted 7Z archives
To create, or extract, an encrypted
.7z file, enter
the password in PeaZip clicking the padlock icon in the status bar
(in the file/archive browser) or below output address
field (in extraction or archiving interfaces), or click Tools >
password / keyfile in main menu, or press F9 accelerator key.
files and folders
inside the archive are marked by * sign.
This format supports AES-based 7Z encryption, which can be optionally
set (form password prompt options) to encrypt file names, rendering
archive table of content (TOC) unreadable without providing correct
password - meaning user will be asked for password for opening
(browsing, searching) those files.
Please note 7z format
supports file-level encryption so multiple passwords can be used in the
same archive to encrypt different group of files - and consequently in
this case different password must be provided to access each part of
the archive, changing password entered in PeaZip.
"Keyfile" field is optional, leave it blank if you don't want to rely
factor authentication - keyfile is the "what you have" element (needs
to be handled safely), password (or passphrase) is the
non-material "what you know" element; both are needed for
recovering the encrypted file content.
Use of keyfile increases security over password
only encryption since also having access to the keyfile will be
required to perform the extraction, eliminating the need of overly
complex passwords to resist to social engineering profiling, and
brute-forcing or dictionary attacks.
External online resources: 7-Zip
official domain, p7zip project POSIX
of 7-Zip for Unix and Unix-like operating systems, 7Z file
specifications, 7Z format
PPMd and LZMA/LZMA2 data
Topics and search suggestions:
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open 7z files (handle compress / decompress, read / write, view
browse & search compressed data), edit existing 7z archive, extract
7z to new folder, drag and drop extraction, tar.xz