Suse & OpenSuse Tips » compression http://www.susetips.com Tricks, Guides, Tutorials, How Tos and Troubleshooting suse linux Sat, 05 Jun 2010 17:55:24 +0000 en hourly 1 http://wordpress.org/?v=3.0.1 Automatically dating your tar backups http://www.susetips.com/2009/05/05/automatically-dating-your-tar-backups/ http://www.susetips.com/2009/05/05/automatically-dating-your-tar-backups/#comments Wed, 06 May 2009 05:38:01 +0000 admin http://www.susetips.com/2009/05/05/automatically-dating-your-tar-backups/ Post from: Suse & OpenSuse Tips
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Automatically dating your tar backups

]]> Normally, we use the tar command coupled with some compression program such as gzip to create a backup of our directories. I.e.

# tar -cf /var/log/backup/tux.tar /home/tux

to backup the home directory of the user tux into the directory  /var/log/backup.

However, if we are going to do this on a regular basis, we will be overwriting the file tux.tar.  This would mean that we will only have one snapshot of the user tux home directory.

To keep copies of backups from different times, you will need to use different filenames, preferably with a date indicator.  You can easily do this by,

# tar –cf /var/log/backup/tux-`date +%F`.tar /home/tux

Of course, if you backup a few times within the day, then you may want to use a different option from the +%F format option.

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Automatically dating your tar backups

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]]> http://www.susetips.com/2009/05/05/automatically-dating-your-tar-backups/feed/ 0 Short and quick tutorial for the command “tar” http://www.susetips.com/2009/04/16/short-and-quick-tutorial-for-the-command-tar/ http://www.susetips.com/2009/04/16/short-and-quick-tutorial-for-the-command-tar/#comments Thu, 16 Apr 2009 10:00:46 +0000 admin http://www.susetips.com/2009/04/16/short-and-quick-tutorial-for-the-command-tar/ Post from: Suse & OpenSuse Tips
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Short and quick tutorial for the command “tar”

]]> We have recently posted about tarball and the use of tar coupled with compression programs to create it.  Here, we will go through three (3) short tutorial on using tar.

To compress a list of files

To compress (the c in the options) a list of files into a specific file (the f in the options) whilst having the tar program to provide progress of it (verbose mode, the v in the option), we use


# tar cvf <tarfile>.tar <list of files>

Leading / will be removed from the archived listing as this will prevent accidental replacement of system files if the file is uncompressed by root.

To uncompress a file

Similarly, we use the same command options where we replace the c with x (for eXtract).

# tar xvf tarfile.tar

This will extract all the files from the archive and recreate the directories and files in the location where the user is in.  Note that, it is good practice to create a new directory, change directory into it before you extract from a tar archive.  This is to prevent overwriting of existing files, unless that is the intention.

To view content of a file

Sometimes, we just want to check if we have a specific file in an archive.  For example, if we are accessing a tape drive (at /dev/st0), we can list (the t in the option) the content using

# tar tvf /dev/st0

More often than not, the listing will be too long for us.  We can pipe the output to grep.

# tar tvf /dev/st0 | grep <string-to-match>

Hope this is short enough.  Leave a comment if you want to ask questions pertaining to tar.

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Short and quick tutorial for the command “tar”

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]]> http://www.susetips.com/2009/04/16/short-and-quick-tutorial-for-the-command-tar/feed/ 0 What are .Z, .gz and .bz2 files? http://www.susetips.com/2009/04/15/what-are-z-gz-and-bz2-files/ http://www.susetips.com/2009/04/15/what-are-z-gz-and-bz2-files/#comments Wed, 15 Apr 2009 07:04:24 +0000 admin http://www.susetips.com/2009/04/15/what-are-z-gz-and-bz2-files/ Post from: Suse & OpenSuse Tips
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What are .Z, .gz and .bz2 files?

]]> As part of a tarball distribution and also other compressed files, you will come across files with the .Z, .gz and .bz2 extensions.  These are basically files that have been compressed using different applications, much like the .zip files predominantly found in the Windows environment.

file-compression


compress for .Z files

The UNIX command compress is used to create and extract files with the .Z extension.  Unfortunately, this is not available on SuSE.  If you need to uncompress .Z files that you downloaded, you can use the command zcat.

gzip and gunzip for .gz files

This is the more common compression program and algorithm that’s used with Linux.

# gzip <filename>
# gunzip <filename>.gz

bzip2 and bunzip2 for .bz2 files

Known to have a more superior compression ratio than gzip but less frequently used.

# bzip2 <filename>
# bunzip2 <filename>.bz2

zip and unzip for .zip files

Being in a world where Windows seems to be the norm, we can’t avoid receiving file that’s compressed with WinZIP or other tools that create .zip file.  Luckily for us, we have zip and unzip for these files.

# zip <archive>.ZIP <filenames>
# unzip <archive>.ZIP

Please comment if you have any further questions.

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What are .Z, .gz and .bz2 files?

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