Kevin Harrison

After mangling some crontabs commands, I finally got the date into mysql exports.

mysqldump -u database-user -h localhost -pdatabase-password database | gzip -9 > /path/to/backup/directory/database-data`date +%m%d%y`.sql.gz

This command will dump the database, gzip it then add the date to the exported file. Basically if you had problems adding a date to the export file you most likely forgot to add a '\' before the %m, %d, or the %y.

edit: well it looks like my blog is actually removing the \ before the %m%d%y in the command. It should look like this minus the spaces...

\ %m \ %d \ %y

create:
tar -cvf mystuff.tar mystuff/
tar -czvf mystuff.tgz mystuff/
extracting:
tar -xvf mystuff.tar
tar -xzvf mystuff.tgz
testing/viewing:
tar -tvf mystuff.tar
tar -tzvf mystuff.tgz

Note that .tgz is the same thing as .tar.gz
Tar "tars up" a bunch of files into one "tar-file"
gzip is compression, but only works on one file, so the entire "tarfile" is compressed.

Also when creating a tar or cpio backup, never, never, never use an "absolute" path -- you have been warned; also linux tar warns you of this too. The problem is that when you want to unpack, you cannot choose where to unpack to, you will be forced to unpack to the "same" absolute path. When creating a tar or cpio you should change the the appropriate directory and tar from there.

Also when creating a tar or cpio it is general good practice to tar up a directory (appropriately named) which contains your files, rather than just the files. This is good courtesy to anyone unpacking your tarfile.

If you would like to create a tar file while saving ownership and permissions, add the "p" flag.

Creating and saving ownership and permissions:
tar -cpvf mystuff.tar mystuff/
tar -cpzvf mystuff.tgz mystuff/

Also take note of the following commands:
gzip
gunzip
cat
zcat
bzcat
bzip2
bunzip2
zgrep
bzgrep

(cd /mydir && tar -czf - .)|(cd /destdir && tar -xzvf -)
tar -czf - . | ssh user@dest "(cd /destdir && tar -xzvf -)"
(cd /mydir && tar -czf - .) | ssh user@dest "(cd /destdir && tar -xzvf -)"

Errors:
If you receive an error such as the following:

[root@localhost test]# ssh user@dest "(cd /rh62/home/kernel && tar -czvf - linux-2.2.22.tar.bz2)"|tar -xzvf -

user@dest's password:

linux-2.2.22.tar.bz2

linux-2.2.22.tar.bz2



gzip: stdin: decompression OK, trailing garbage ignored

tar: Child returned status 2

tar: Error exit delayed from previous errors

[root@localhost test]#

Then try leaving off the compression as follows:

[root@localhost test]# ssh user@dest "(cd /rh62/home/kernel && tar -cvf - linux-2.2.22.tar.bz2)"|tar -xvf -

user@dest's password:

linux-2.2.22.tar.bz2

linux-2.2.22.tar.bz2

[root@localhost test]# echo $?

0

[root@localhost test]# 

Spaces in your filenames?
Having fun with spaces in the filename or directory name? Here's your answer:

find . -type f -name '*jpg' | grep " " | while read REPLY; do

     tar -cf - "$REPLY" | (cd /tmp/jpg && tar -xvf -)

done

Bonus:

find . -type f | while read REPLY; do

     cp -a "$REPLY" /tmp/jpg/`echo $REPLY \

       | sed -e 's/ //g' -e 's/\///g' -e 's/^\._//'`

done



ssh root@dest 'tar -C / -czf - --exclude ./proc/* --exclude ./dev/pts/* .' > gmaster.tgz

proc and dev was empty for the following command, so I didn't exclude them:

tar -czf - . | ssh user@dest "cat - > k12ltsp.master.tgz"

Don't use the find command, use grep.

grep -R "the word that is being looked for" /the/folder/to/search

That's it. Well that's it if you don't use |less or any other delimiter. This command is perfect for debugging code, especially when your website is not valid html. Searching through different templates can be very daunting, GREP makes it easy.