Monday, May 2, 2011

Linux Commands

tar Commands

1. Creating an uncompressed tar achieve.

tar cvf filename.tar filename/foldername


In the above command:
  • c – create a new archive
  • v – verbosely list files which are processed.
  • f – following is the archive file name
ex:

tar cvf abc.tar myfile.txt
tar cvf pqr.tar myfolder

2.
Creating a tar gzipped archieve using option cvzf


To use gzip compression on the tar archive, use the z option as follows.

tar cvzf filename.tar.gz dirname/

tar cvzf filename.tar.gz filename

In the above command

  • c – create a new archive
  • v – verbosely list files which are processed.
  • f – following is the archive file name
  • z– filter the archive through gzip
ex:

tar cvzf filename.tar.gz filename.txt

3. Extracting (untar) a file using tar command

tar xvf filename.tar

In the above command

  • x – extract files from archive.
  • v – verbosely list files which are processed.
  • f – following is the archive file name

ex:

tar xvf filename.tar

4. Extracting a gziped tar achieve.

tar xvfz filename.tar.gz

In the above command
  • x – extract files from archive.
  • v – verbosely list files which are processed.
  • f – following is the archive file name
  • z- uncompressing a gzipped tar achieve.

tail Command

Example 1:

tail mytextfile.txt
-  The above command list the last 10 lines of the file "mytextfile.txt"

tail mytextfile.txt -n 100

- The above command list last 100 lines of the file "mytextfile.txt"

tail -f mytextfile.txt 
- The above command displays the last 10 lines and then update the file as new lines are being added
- This is a very useful command to watch log files in realtime

tail -f access.log | grep 127.0.0.2

- The above command can use to filter the output of the file

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