Tar: Difference between revisions

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GNU Tar is everybody's favorite archive file format.

== Use Cases ==

=== Get just one file ===

<code>drush archive-backup (arb)</code> and <code>drush archive-restore (arr)</code> are great commands for making a full site backup prior to changes; that you can use to restore from. Your entire Drupal instance (code, settings, modules, plus database) are all tar'd into an archive file, and gzip compressed <ref>The example refers to a .tar file. <code>drush archive-backup</code> creates a .tar.gz file -- meaning it's compressed with gzip. So, to work with the .tar file, first you would uncompress the .tar.gz file with <code>gunzip file.tar.gz</code></ref>. Again, one of the things that <code>drush arb</code> does is create a SQL dump file. What if you want just that dump file from the archive? The long way would be to extract the whole thing, find and move the bits you want, and then discard the rest. Or, you could just tell tar to give you the file you want explicitly:

# look at what's in the archive

tar -tf ~/drush-backups/archive-dump/20150327030955/freephile_drupal.20150327_030955.tar

# request just the SQL dump file (puts it into the current working directory)

tar -xf ~/drush-backups/archive-dump/20150327030955/freephile_drupal.20150327_030955.tar freephile_drupal.sql

</syntaxhighlight>

=== Strip top level of the archive and don't extract a sub-folder ===

The magic tar one-line command to unpack a Drupal distribution over an

existing Drupal directory (without ~~nuking~~ sites) ~~- but keep reading!~~

existing Drupal directory (without clobbering your "sites" directory)

<~~source~~ lang="bash">

tar x --show-omitted-dirs --exclude sites --directory ../work/gr/iic-drupal/ \

--strip 1 -zf drupal-6.11.tar.gz

</~~source~~>

</syntaxhighlight>

--

Drupal ships a tarball with the first object being a directory named

after the release (e.g. drupal-6.11/)

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But, if you want to do it all in one pass, you can use the combination

of '''strip''' and '''directory''' options:

<~~source~~ lang="bash">

tar x --directory ~/existing-drupal --strip 1 -zf drupal-6.11.tar.gz

</~~source~~>

</syntaxhighlight>

~~But wait!! that command will still overwrite your existing "sites"~~

~~directory which is where you are supposed to store all your~~

;<code>--strip 1</code> : removes the first path component of objects in the tar archive

~~customizations to Drupal~~ -- ~~and you don't want~~ to ~~do that. The~~

;<code>--directory</code> : tells tar to change to a particular directory prior to extracting the contents of the archive

~~recommended procedure is~~ to ~~make backups~~ of ~~your~~ "sites" directory ~~and~~

~~then copy it back into the distribution that you unpack~~. ~~I think a~~

If you're upgrading a Drupal instance, then you already have a "sites" directory. You can skip over this directory in the tar archive with the '''exclude''' option. In

~~better way is to~~ skip over ~~the sites~~ directory~~. Don't even extract it~~

~~from~~ the tar archive~~. You can do this~~ with the '''exclude''' option. In

fact, you can even have tar show you what you have skipped over with

the '''show-omitted-dirs''' option. So, the best way that I know how to

unpack a Drupal archive over an existing installation - all in one

easy command - is

<~~source~~ lang="bash">

tar x --show-omitted-dirs --exclude sites --directory ../work/gr/iic-drupal/ --strip 1 -zf drupal-6.11.tar.gz

</~~source~~>

</syntaxhighlight>

This didn't mess with my .git directory, .gitignore file and another

top-level file I had called "crossdomain.xml" ~~but it still nuked~~ my

top-level file I had called "crossdomain.xml"

"sites" directory ~~:-(~~

== Warning ==

{{Messagebox |

|type=warning

|text = Although I could not reproduce this behavior, I did once get my "sites" directory deleted. So, you do have [[backups]] and use [[version control]] right?

}}

I restored it with

<~~source~~ lang="bash">

git checkout sites

</~~source~~>

</syntaxhighlight>

and then I did a

<~~source~~ lang="bash">

git status

</~~source~~>

</syntaxhighlight>

followed by

<~~source~~ lang="bash">

git commit -a -m 'adds changes in Drupal 6.11 security release'

</~~source~~>

</syntaxhighlight>

== Documentation ==

There is a ~~'''~~lot~~'''~~ more option information in the <code>tar --help</code> output

There is a lot more option information in the '''<code>tar --help</code>''' output

than in the man page. The "info" manual is also online at http://www.gnu.org/software/tar/manual/tar.html providing full documentation for tar.

than in the man page. Of course if you <code>sudo apt-get install tar-doc</code> then you can view the info manual. The "info" manual is also online at http://www.gnu.org/software/tar/manual/tar.html providing full documentation for tar.

~~I'll have to test --keep-newer-files to see if that works.~~

== Alternatives ==

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from

http://www.cs.toronto.edu/~murray/code/hacks/untar

<~~source~~ lang="bash">

#!/bin/bash

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fi

done

</~~source~~>

</syntaxhighlight>

== See Also ==

Sometimes you end up with a directory nested in it's intended destination (like drush arb can leave you with /var/www/drupal/drupal). See the [[Bash]] article for moving a nested directory up a level.

@@ Line 1: / Line 1: @@
+GNU Tar is everybody's favorite archive file format.
+== Use Cases ==
+=== Get just one file ===
+<code>drush archive-backup (arb)</code> and <code>drush archive-restore (arr)</code> are great commands for making a full site backup prior to changes; that you can use to restore from.  Your entire Drupal instance (code, settings, modules, plus database) are all tar'd into an archive file, and gzip compressed <ref>The example refers to a .tar file.  <code>drush archive-backup</code> creates a .tar.gz file -- meaning it's compressed with gzip.  So, to work with the .tar file, first you would uncompress the .tar.gz file with <code>gunzip file.tar.gz</code></ref>.  Again, one of the things that <code>drush arb</code> does is create a SQL dump file.  What if you want just that dump file from the archive?  The long way would be to extract the whole thing, find and move the bits you want, and then discard the rest.  Or, you could just tell tar to give you the file you want explicitly:
+<syntaxhighlight lang="bash">
+# look at what's in the archive
+tar -tf ~/drush-backups/archive-dump/20150327030955/freephile_drupal.20150327_030955.tar
+# request just the SQL dump file (puts it into the current working directory)
+tar -xf ~/drush-backups/archive-dump/20150327030955/freephile_drupal.20150327_030955.tar freephile_drupal.sql
+</syntaxhighlight>
+=== Strip top level of the archive and don't extract a sub-folder ===
 The magic tar one-line command to unpack a Drupal distribution over an
-existing Drupal directory (without nuking sites) - but keep reading!
+existing Drupal directory (without clobbering your "sites" directory)
-<source lang="bash">
+<syntaxhighlight lang="bash">
 tar x --show-omitted-dirs --exclude sites --directory ../work/gr/iic-drupal/ \
 --strip 1 -zf drupal-6.11.tar.gz
-</source>
+</syntaxhighlight>
---
 Drupal ships a tarball with the first object being a directory named
 after the release (e.g. drupal-6.11/)
@@ Line 23: / Line 35: @@
 But, if you want to do it all in one pass, you can use the combination
 of '''strip''' and '''directory''' options:
-<source lang="bash">
+<syntaxhighlight lang="bash">
 tar x --directory ~/existing-drupal --strip 1 -zf drupal-6.11.tar.gz
-</source>
+</syntaxhighlight>
-But wait!! that command will still overwrite your existing "sites"
-directory which is where you are supposed to store all your
+;<code>--strip 1</code> : removes the first path component of objects in the tar archive
-customizations to Drupal -- and you don't want to do that.  The
+;<code>--directory</code> : tells tar to change to a particular directory prior to extracting the contents of the archive
-recommended procedure is to make backups of your "sites" directory and
-then copy it back into the distribution that you unpack.  I think a
+If you're upgrading a Drupal instance, then you already have a "sites" directory.   You can skip over this directory in the tar archive with the '''exclude''' option.  In
-better way is to skip over the sites directory.  Don't even extract it
-from the tar archive.  You can do this with the '''exclude''' option.  In
 fact, you can even have tar show you what you have skipped over with
 the '''show-omitted-dirs''' option.  So, the best way that I know how to
 unpack a Drupal archive over an existing installation - all in one
 easy command - is
-<source lang="bash">
+<syntaxhighlight lang="bash">
 tar x --show-omitted-dirs --exclude sites --directory ../work/gr/iic-drupal/ --strip 1 -zf drupal-6.11.tar.gz
-</source>
+</syntaxhighlight>
 This didn't mess with my .git directory, .gitignore file and another
-top-level file I had called "crossdomain.xml" but it still nuked my
+top-level file I had called "crossdomain.xml"
-"sites" directory :-(
+== Warning ==
+{{Messagebox |
+|type=warning
+|text = Although I could not reproduce this behavior, I did once get my "sites" directory deleted.   So, you do have [[backups]] and use [[version control]] right?
+}}
 I restored it with
-<source lang="bash">
+<syntaxhighlight lang="bash">
 git checkout sites
-</source>
+</syntaxhighlight>
 and then I did a
-<source lang="bash">
+<syntaxhighlight lang="bash">
 git status
-</source>
+</syntaxhighlight>
 followed by
-<source lang="bash">
+<syntaxhighlight lang="bash">
 git commit -a -m 'adds changes in Drupal 6.11 security release'
-</source>
+</syntaxhighlight>
 == Documentation ==
-There is a '''lot''' more option information in the <code>tar --help</code> output
+There is a lot more option information in the '''<code>tar --help</code>''' output
-than in the man page.  The "info" manual is also online at http://www.gnu.org/software/tar/manual/tar.html providing full documentation for tar.
+than in the man page.  Of course if you <code>sudo apt-get install tar-doc</code> then you can view the info manual.  The "info" manual is also online at http://www.gnu.org/software/tar/manual/tar.html providing full documentation for tar.
-I'll have to test  --keep-newer-files to see if that works.
 == Alternatives ==
@@ Line 73: / Line 84: @@
 from
 http://www.cs.toronto.edu/~murray/code/hacks/untar
-<source lang="bash">
+<syntaxhighlight lang="bash">
 #!/bin/bash
@@ Line 336: / Line 347: @@
 fi
 done
-</source>
+</syntaxhighlight>
+== See Also ==
+Sometimes you end up with a directory nested in it's intended destination (like drush arb can leave you with /var/www/drupal/drupal). See the [[Bash]] article for moving a nested directory up a level.
+{{References}}