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How to check the GNU version of the tar archiving utility


How to check the GNU version of the tar archiving utility

How to check the GNU version of the tar archiving utility

1. tar name in linux

tar [man page] – The GNU version of the tar archiving utility

2. tar synopsis

tar  [ - ] A --catenate --concatenate | c --create 
| d --diff --compare | --delete | r --append 
| t --list | u --update | x --extract  --get  [ options ]
 pathname [ pathname ... ]
3. tar frequently used options
-f, --file [HOSTNAME:]F
use archive file or device F (default "-", 
meaning stdin/stdout)
-j, --bzip2 filter archive through bzip2,  
use  to  decompress  .bz2  files.
-N, --after-date DATE, --newer DATE
      only store files newer than DATE
-v, --verbose
      verbosely list files processed
-w, --interactive, --confirmation
      ask for confirmation for every action
-z, --gzip, --gunzip, --ungzip
      filter the archive through gzip
4. tar examples in linux

For the sake of simplicity we show linux tar examples without using a tape drive. Many of the tar examples can be translated to use tape drive. For example: Create a archive of /etc/ directory to a file etc.tar

tar -cf etc.tar /etc

to create a archive to the tape (/dev/st0 ) instead of archive file we can translate this command to:

tar -cf /dev/st0 /etc

During this tar tutorial we will use “archivewithtar/” directory as sample directory. Here is a content of this sample directory: archive directory with tar
Create an archive to linuxtarfile.tar file of the archivewithtar/ directory:

tar cf linuxtarfile.tar archivewithtar/

archive directory with tar to a file
To see what files are being archived by tar command we can use – v ( tar verbose mode ):

tar cf linuxtarfile.tar archivewithtar/

tar archive with verbose mode
To instruct tar command to list all files within a archive file we can use command:

tar tf linuxtarfile.tar

make tar to list all files within an archive
To extract just particular files from a tar archive file we need to replace “c” option with “x”. Here we extract archivewithtar/dmesg to a restore/ directory.

tar xvf linuxtarfile.tar archivewithtar/dmesg

tar - extract just particular file
Extract entire contents of the tar archive linuxtarfile.tar file to restore/ directory:

tar xvf ../linuxtarfile.tar

Extract entire contents of the tar archive
Linux tar archive command does not use compression by default. Most commonly used compression types with tar command are -z ( gzip ) and -j ( bzip2 ). Create compressed archive of archivewithtar/ with gzip and bzip2:

tar czf linuxtarfile.tar.gz archivewithtar/ tar cjf linuxtarfile.tar.bz2 archivewithtar/

Compare the size of all three tar archives files: no compression, gzip and bzip2: create compressed archive with tar
The approach to extract files from compressed tar archive is the same as to extract data from non-compressed tar archive. Here we extract files from gzip compressed tar archive file:

tar xvzf linuxtarfile.tar.gz

extract compressed archive with tar
Linux tar archive command can create simple incremental or differential backup with -N or –newer option. Let’s consider two files in our archivewithtar/ which have different change time:

simple tar incremental or differential backup
Use tar to archive files newer than “7.2.2008 13:54:00” ( make sure to you use correct tar date format !):

tar cvf linuxtarfile.tar --newer  "2008-02-07 13:54:00" archivewithtar/

simple tar incremental or differential backup newer
Tar command in interactive mode gives us an option which files to extract:

tar xvjwf linuxtarfile.tar.bz2

interactive tar to extract particular files
Use -p ( –preserve-permissions )tar option to preserve permissions file permission:

tar czfp linuxtarfile.tar.gz archivewithtar/

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