1.f Archive, compress, unpack, and uncompress files using tar, star, gzip, and bzip2...
Definition...
- Compression - encoding information in fewer bits
- Archive - a file that is a collection of other files that can be managed easier (sorted, moving, copying, etc...)
Archive...
tar...
'tar' stands for "TApe ARchive".
Usages...
Create a tar archive
tax -cvf [archive].tar [file(s)|folder]
Extract a tar archive
tar -xvf [archive].tar
Show all files of an archive:
tar -tvf [archive].tar
Tar with compression...
With gunzip
Create a compressed tar archive
tar -czvf [archive].tar.gz [file(s)|folder]
Extract a compressed tar archive
tar -xzvf [archive].tar.gz
With bzip2
Create compressed tar archive
tar -cjvf [archive].tar.bz2 [file(s)|folder]
Extract a compressed tar archive
tar -xjvf [archive].tar.bz2
star - unique standard tape archiver...
star is another implementation of tar. It looks like it supported SELinux context before tar (however tar now also supports extended file attributes as well as SELinux, so I'm not sure if this is really needed for the exam).
Usage Examples...
Create an archive
# star -c –f=compressed.star [file list]
Extract archive
# star –x –f=compressed.star
Create an archive retaining SELinux context
# star -xattr -H=exustar -c -f=test.star file{1,2,3}
Snippet from RHEL 6 documentation page
Compression...
The main difference between the different compress commands is the algorithm that they use.
Compression commands:
- gzip (1) - compress or expand files
- bzip2 (1) - a block-sorting file compressor, v1.0.6
- zip (1) - package and compress (archive) files
- unzip (1) - list, test and extract compressed files in a ZIP archive
gunzip...
Create a compressed file
gzip file
Result: file.gz
Decompress a file:
gzip -d file
bzip2...
Create a compressed file
bzip2 file
Result: file.bz2
Decompress a file
bzip2 -d file.bz2
zip/unzip...
Combining individual files in a compressed archive:
zip archive.zip file1 file2
Combining complete folders in a compressed archive:
zip -r archive.zip folder1 folder2 folder3
Decompress and extract an archive:
unzip archive.zip
Show all files of an archive:
unzip -l archive.zip
Notes:
- Use
-don bothgzipandbzip2to extract. Forunzip, the command itself specifies that it's extracting (-dis used for destination folder) - For gzip you can specify the compression level with a number (eg:
-5) - Extension name is not required. It's only used for human reference
Viewing compressed files...
You can use the following commands to view compressed files:
zcatgunzip -cbzip2 -czlessvim