Linux Compression/Decompression Commands

There are some utilities for compression and decompression on Linux that are used often. Now I’ll explain their usages one by one.

Suppose we have files a.txt, b.txt, c.txt and folders aa, bb, cc in the current folder.

bzip2 There are two styles of using bzip2 Style 1 (recommended)
```
bzip2 -z a.txt
bzip2 -d a.txt.bz2
```
Style 2
```
bzip2 a.txt
bunzip2 a.txt.bz2
```
Note. bunzip2 = bzip2 –decompress. By default, the original file will be deleted. If you want to keep the original file, add -k.
```
bzip2 -zk a.txt
bzip2 -dk a.txt.bz2
```
xz xz is very similar to bzip2. They are almost the same in usage. Style 1 (recommended)
```
xz -z a.txt
xz -d a.txt.xz
```
Style 2
```
xz a.txt
unxz a.txt.xz
```
Note. unxz = xz –decompress If you want to keep the original file, add -k
```
xz -zk a.txt
xz -dk a.txt.xz
```
lzma lzma is very similar to xz. They are almost the same in usage. Style 1 (recommended)
```
lzma -z a.txt
lzma -d a.txt.lzma
```
Style 2
```
lzma a.txt
unlzma a.txt.lzma
```
Note. unlzma = lzma –decompress If you want to keep the original file, add -k
```
lzma -zk a.txt
lzma -dk a.txt.lzma
```
gzip gzip has a little difference in usage from bzip2, xz and lzma. gzip doesn’t have -z option. So if you want to compress, you don’t add anything. Style 1 (recommended)
```
gzip a.txt
gzip -d a.txt.gz
```
Style 2
```
gzip a.txt
gunzip a.txt.gz
```
The way of keeping the original file is also different. gzip doesn’t have -k option, but it provides -c option for both compression and decompression, which writes on standard output and keeps original file unchanged.(bzip2, xz, lzma only provides -c option for decompression.) Thus we can use
```
gzip -c a.txt > a.txt.gz
gzip -dc a.txt.gz > a.txt
```
to keep the original file.

zip zip can compress a batch of files into a single .zip file, while maintaining their folder structure. The basic command line looks like

zip [options] out_file in_file1 in_file2 ...

Examples

zip out.zip a.txt b.txt c.txt #compress files a.txt, b.txt, c.txt into out.zip
zip -r out.zip aa bb cc #compress folders aa, bb, cc into out.zip, -r means recursively

Use unzip for decompression

unzip out.zip #decompressed into the current folder
unzip -d out out.zip #decompressed into folder out/, which is created if not exists

7z 7z can also compress and decompress a batch of files and keep their folder structure. It uses a for compression and x for decompression.

7z a out.7z a.txt b.txt c.txt
7z a out.7z aa bb cc #automatically recursive for folders
7z x out.7z #decompressed into the current folder
7z x -oout out.7z #decompressed into folder out/, which is created if not exists

Note. Don’t add spaces after -o option.

rar rar can also compress and decompress a batch of files and keep their folder structure. It uses a for compression and x for decompression.

rar a out.rar a.txt b.txt c.txt
rar a out.rar aa bb cc #automatically recursive for folders
rar x out.rar #decompressed into the current folder
rar x out.rar out/ #decompressed into folder out/, which is created if not exists

Note. The backslash / at the end of the output folder cannot be omitted. The decompression can also be done using unrar

unrar x out.rar #decompressed into the current folder
unrar x out.rar out/ #decompressed into folder out/, which is created if not exists

Note. The backslash / at the end of the output folder cannot be omitted.

tar Strictly speaking, tar is not a compression/decompression tool, but an archiving tool. To use tar, first get to know the following options

-c, create an archive
-x, extract from an archive
-v, verbose
-f file, set the archive to file
-C DIR, change to directory to DIR (all operations are based on that directory)
-z, gzip
-j, bzip2
-J, xz
--lzma, lzma

Examples

tar -cvf out.tar a.txt b.txt c.txt
tar -cvf out.tar aa bb cc #automatically recursive for folders
tar -xvf out.tar #decompressed into the current folder
tar -zcvf out.tar.gz aa bb cc #using gzip compression
tar -zxvf out.tar.gz -C out #decompressed into folder out/, which is NOT automatically created