7-Zip. The 7za.exe program is used to compress, extract and update files through the command line. It provides superior compression. It is a great program.
Tip: For convenience and so you don't need to change environment paths, put the 7za.exe file in your user directory.
Next: Open the Windows console and test the 7za.exe program out with a few commands. Type in the exe name 7za and this will display.
Grammar: We see the grammar we need to use with 7za.exe. The "command" is the main verb.Switches: Then you specify optional switches, the archive name (source or destination) and files. My user directory is "C:\Users\Sam\".
7-Zip default output 7-Zip (A) 4.60 beta Copyright (c) 1999-2008 Igor Pavlov 2008-08-19 Usage: 7za <command> [<switches>...] <archive_name> [<file_names>...] [<@listfiles...>]Command a. You can use the "a" command with the single letter a. This command stands for "archive" or "add." Use it to put files in an archive.
Arguments: You have to specify the destination archive, and the source files (in that order).
Note: On the test system, "C:\Users\Sam" contains two files (file1.txt and file2.txt). The command puts those two files in an archive.
Tip: To open your archive, right click on it and select 7-Zip -> Open archive. The screenshot shows the files compressed in files.7z.
C:\Users\Sam>7za a -t7z files.7z *.txt 7-Zip (A) 4.60 beta Copyright (c) 1999-2008 Igor Pavlov 2008-08-19 Scanning Creating archive files.7z Compressing file1.txt Compressing file2.txt Everything is Ok C:\Users\Sam>Command d. We use the "d" command in 7-Zip command lines. This stands for delete. It allows you to remove a certain file (or set of files) from inside an archive.
Note: You will need this if you use huge archives and need to save time. This is from the manual.
Tip: You can also remove a single file from an archive with "d". This is more useful when you do not have a solid archive.
7z d archive.zip *.bak -r 7z: use executable d: delete files archive.zip: delete from this archive *.bak: only match bak files -r: traverse all subdirectoriesCommand e. The "e" stands for extract, and it means to unzip or expand an archive. You must specify the source archive always, and may also specify a destination.
Info: The "e" command extracts everything to a specified directory. Another command "x" can preserve directory structures in archives.
Overwrite prompts: 7-Zip will always prompt you if there is a file it needs to overwrite to extract the new file.
However: This can be problematic if you are scripting or embedding 7za.exe. In that case, see the -y switch.
7z e archive.zip 7z: executable e: use extract command archive.zip: source archive you want to expandCommand l. The lowercase L is used to list the contents of archives. You probably will not need to use it often. I thought I would test it and show an example.
Next: This shows the listing of a solid archive. The originals are 27216 bytes and 3888 bytes. They compress down to 1030 bytes.
C:\Users\Sam>7za l files.7z 7-Zip (A) 4.60 beta Copyright (c) 1999-2008 Igor Pavlov 2008-08-19 Listing archive: files.7z Method = LZMA Solid = + Blocks = 1 Physical Size = 1202 Headers Size = 172 Date Time Attr Size Compressed Name ------------------- ----- ------------ ------------ ------------------------ 2008-10-02 15:48:01 ....A 27216 1030 file1.txt 2008-10-02 15:47:45 ....A 3888 file2.txt ------------------- ----- ------------ ------------ ------------------------ 31104 1030 2 files, 0 foldersCommand t. Here we use the "t" command in the 7z program. This command allows you to test the integrity of archives. It stands for 'test' and is much less useful than the "-t" switch.
Warning: Don't confuse the two. This one is used for diagnostics. We usually want the hyphen "-t."
7z t archive.zip *.doc -r 7z: use this executable t: test the specified archive archive.zip: the archive you want to test *.doc: test all these files in the archive -r: recurse all child directoriesCommand u. This stands for update. This command replaces old files in your archive with newer files. This prevents needing to decompress and recompress the entire archive.
Warning: The "u" command doesn't work with solid archives. A solid archive is one where all the files are compressed together.
So: You cannot update specific files in solid archives with the "u" command. Solid archives are limited.
7z u archive.zip *.doc 7z: executable name u: update command archive.zip: archive you want to update files in *.doc: only update these files (Word documents)Switch m. We can change the optimization settings in 7-Zip on the command line. This is the most important and useful option you can use.
Tip: It specifies the method of compression. Here I will show a bunch of options, and also some examples.
Compression levels: Switch -mx0: Don't compress at all. This is called "copy mode." Switch -mx1: Low compression. This is called "fastest" mode. Switch -mx3: Fast compression mode. Will automatically set various parameters. Switch -mx5: Same as above, but "normal." Switch -mx7: This means "maximum" compression. Switch -mx9: This means "ultra" compression. You probably want to use this.Switch m, advanced. Here are advanced compression method (-m) switches. The first three are usually of limited use. My experience is that manual optimizations doesn't produce big benefits.
Switch -mfb: Specifies number of fast bytes. Sometimes helps with "sparse" files. Don't bother.Switch -mpass: Number of passes for deflate compression. Don't bother with this. Automatically set with levels.Switch -md: This specifies dictionary size. It is automatically set, so don't bother.Switch -mmt: Enable multithreading. Use if you have quad-core and a huge archive. Specify "on" or "off". This may be enabled by default.
7z x archive.zip 7z: executable name x: use the extract command archive.zip: the archive you want to extract all the files fromSwitch t type. Here I show how to specify the archive type. Note that you can specify any file name you want for any type. But some extensions are recommended—they are standard.
Type switches Switch: -t7z Format: 7Z Example filename: archive.7z (default option) Switch: -tgzip Format: GZIP Example filename: archive.gzip, archive.gz Switch: -tzip Format: ZIP Example filename: archive.zip (compatible) Switch: -tbzip2 Format: BZIP2 Example filename: archive.bzip2 Switch: -ttar Format: TAR Example filename: tarball.tar (UNIX and Linux) Switch: -tiso Format: ISO Example filename: image.iso (may not be supported) Switch: -tudf Format: UDF Example filename: disk.udfType switch examples. The 7-Zip manual shows the -tiso and -tudf switches. These are not the most common. Almost all of the examples in this document use -t switches.
7z a -tiso archive.iso 7z a -tudf archive.udf 7z: executable name a: add to archive -tiso or -tudf: format of archive to create archive.iso or archive.udf: name of archive to createSolid archives. 7z is the only file format in 7-Zip that you can specify whether the archive is solid or not. Solid makes it impossible to use the "u" command to update individual files.
Switch -ms=on: Enable solid mode. This is the default so you won't often need to specify it.Switch -ms=off: Disable solid mode. Useful when you need to update individual files. Will reduce compression ratios normally.
PPMd switch -mmem=24b, -mmem=24k, -mmem=24m: These control the amount of memory you use. They are useful and higher is normally better.PPMd switch -mo=2, -mo=32: These specify the model order in PPMd. They are not normally useful.
Tip: You should use PPMd when you have a large corpus (body) of text. This could include HTML. It can improve ratios by around 30%.
7z a -tzip archive.zip *.jpg -mx0 7z: name of executable a: add to archive command -tzip: specify a ZIP archive (useful for compatibility) archive.zip: destination archive *.jpg: only add jpg files to archive -mx0: don't compress, just copy useful for already-compressed filesExample of 7z format. This next command line shows how to create a solid 7z archive of program files (executables). It uses multithreading mode, which means it will be fast.
7z a -t7z archive.7z *.exe *.dll -ms -mmt 7z: name of executable a: archive command specified -t7z: use 7z file type (less compatible and smaller results) archive.7z: destination archive file *.exe: include all *.exe files in directory in new archive *.dll: include all *.dll files in new archive -ms: create solid archive (default) -mmt: multithread the operation (faster)Create PPMd archive. PPMd is an extraordinary algorithm for compressing text. Here I show a command in the 7-Zip manual that compresses all the text files in the working directory.
Tip: The command is useful because you will normally want to only compress text files with PPMd.PPMd Compression
7z a -t7z archive.7z *.txt -m0=PPMd 7z: executable name/path a: add command specified -t7z: use the 7z format (needed for PPMd) archive.7z: destination archive file *.txt: select all text files -mo=PPMd: compress with this algorithmSwitch o. Sometimes you do not want to extract to the current directory. This is where -o can come in handy. Use this to set the destination directory.
7z x archive.zip -oC:\Doc 7z: executable name x: extract archive with paths intact archive.zip: archive to extract files from -oC:\Doc: extract all files to the Doc folder on the C: driveSwitch p. We can use the "-p" switch, which refers to the word "password". This is really helpful when security and encryption is involved. You can specify a password on the command line.
7za a pw.7z *.txt -pSECRET 7za: name and path of 7-Zip executable a: add to archive pw.7z: name of destination archive *.txt: add all text files to destination archive -pSECRET: specify the password "SECRET"Opening password-protected archives. This next console output shows what happens when you try to open the password-protected archive. The password here is SECRET. I am so clever.
Header encryption: Add -mhe to encrypt headers. The password command will automatically deal with encrypted headers.
Tip: Remember, encrypted headers will hide the names of the files in your archive.
C:\Users\Sam>7za x pw.7z 7-Zip (A) 4.60 beta Copyright (c) 1999-2008 Igor Pavlov 2008-08-19 Processing archive: pw.7z Enter password:More switches. Here we take a closer look at more switches that are of limited use. They are sometimes useful to know. Usually you can do better just by using the defaults.
Switch -ssc: Specify case-sensitive mode. The default is -ssc- on Windows (insensitive). The default is -scc on Linux (sensitive).Switch -ssw: Compress locked files. You can try this if you have problems opening files.Switch -w: Set working directory. You can use this when you want to specify temp folders.
7za.exe a archive.7z Z*.* -ssc 7za.exe: 7-Zip command-line executable path and name a: archive command archive.7z: add files to this target archive Z*.*: select only files whose first letter is a capital ZSwitch v. In data compression, a volume is a segment of a data set that is a certain number of bytes long. The volume switch specifies the exact size in bytes, kilobytes or megabytes.
Also: You can specify sequential volumes with the "v" switch on the 7za.exe command line.
Switch -aoa: This switch overwrites all destination files. Use it when the new versions are preferred.Switch -aos: Skip over existing files without overwriting. Use this for files where the earliest version is most important.Switch -aou: Avoid name collisions. New files extracted will have a number appending to their names. You will have to deal with them later.Switch -aot: Rename existing files. This will not rename the new files, just the old ones already there.
Examples: 7z x test.zip -aoa 7z: use the 7-zip executable x: use the extract command test.zip: extract files from this archive -aoa: overwrite all existing filesMultiple files. To add many files to one archive, please use the "a" command and the wildcard * symbol. Specify the name of the destination archive file and the source files afterwards.
Example: For example, *.txt means all text files. You can use the wildcard anywhere.
7z a -tzip archive.zip subdir\ 7z: use executable a: add to archive -tzip: use zip compression archive.zip: create this archive subdir\: source directoryHow do I use BZip2? You can use BZip2 by specifying the "-tbzip2" switch. This can be combined with any compression level. The modes in 7-Zip automatically use many different settings.
Tip: Change the archive not to be solid if you want to update it. Search this page for "solid".
7z e archive.zip -oC:\soft *.cpp -r 7z: executable e: use extract command archive.zip: source archive you want to extract from -oC:\soft: the destination folder (-o is the switch and C:\soft is the argument) *.cpp: only extract cpp files (C++) -r: traverse all subdirectoriesHow can I see what's inside an archive? Use the "l" command. You might want to use "l" in a utility that you run from a command line to make sure your batch archiving properly works.
So: If you want to exclude "file1.txt", use the switch "-x!file1.txt". Please include the hyphen and exclamation.
Note: Use -aos if your files don't change over time and overwriting would just be a waste.
Filters: You can change compression filters, which change behaviors on executable files such as *.exe and *.dll.
And: You can enable header compression and encryption (-mhc=on and -mhe=on). Header compression is by default enabled.