Tar & RPM

Tar Files

Tar files are used to create archive files. Multiple files and directories can be archived into a single file by using the tar command. Keep in mind that tar does not perform compression.

Options

The most commonly used options in tar are –

-c	create archive
-x	extract archive
-v	verbosely list processed files
-f	the output would be a file
-t	displays content of an archive
-p	Preserve permission
-z	used for gzip
-j	used for bzip2

Syntax

tar  –cvf  archive.tar   file1 file2 file3 file4

Example – suppose you have to create a tar file (example.tar) with 3 files f1, f2, f3. Then the command would be –

# tar  -cvf   example.tar  f1 f2 f3

Given below are some examples

1 # tar xvf  example.tar

Extracts the archive example.tar in pwd to obtain original files

2 #  tar tvf example.tar

Shows the contents of the archive example.tar

3 #  tar  pcvf  example2.tar  f1  f2  f3

Creates an archive example2.tar and preserves permission of the original files f1, f2, f3

gzip

As mentioned earlier, tar performs no compression. To compress the archive, gzip can be used. gzip has some additional options –

-1	fastest compression regardless of the compression ratio
-9	best possible compression ratio regardless of the time needed

# gzip  example.tar	compresses the archive example.tar and creates a file example.tar.gz
# gunzip  example.tar.gz	extracts the compressed archive example.tar.gz
# gzip -1 example2.tar	performs fastest compression
# gzip -9 example2.tar	performs best compression
Alternative method
#  tar  zcvf  example.tar.gz  f1 f2 f3	creates a compressed archive example.tar.gz with the files f1, f2 and f3
#  tar  zxvf  example.tar.gz	extracts the compressed archive example.tar.gz

bzip2

bzip2 is a more powerful compression tool than gzip. bzip2 is the upgrade of the original bzip. bzip2 also supports fastest and best compression.

# bzip  example.tar	compresses the archive example.tar and creates a file example.tar.bz2
#  bunzip2  example.tar.bz2	extracts the compressed archive example.tar.bz2
# bzip2 -1 example2.tar	performs fastest compression
# bzip2 -9 example2.tar	performs best compression
Alternative method
#  tar  jcvf  example.tar.bz2  f1 f2 f3	creates a compressed archive example.tar.bz2 with the files f1, f2 and f3
#  tar  jxvf  example.tar.bz2	extracts the compressed archive example.tar.bz2

RPM

RPM or Relational Package Manager is used to install packages/software into the system. RPM can be setup using the following command

# rpm –ivh rpm_name

                  -i = install

       -v = show output verbosely

                  -h = show progress with #

RPM sometimes creates dependency problems. For example, if A.rpm requires B.rpm to be previously installed, then A.rpm cannot be installed unless B.rpm is installed first.

To install A.rpm ignoring dependency, the following command may be used, but it is very likely that the package will not work properly.

# rpm –ivh A.rpm –no-deps

To check whether an RPM is installed, the following commands can be used

# rpm –q RPM1	Checks whether package RPM1 is installed.
# rpm –qa	Shows all installed RPM
# rpm –ql RPM2	Shows locations of all files created during the installation process of RPM2