Linux – extract rar files to folder

I contacted RARLabs support and recieved a response. It turns out that RAR.EXE can handle streaming input similar to how gzip works. You just need to specify the -si option:

   -si[name]
     Read data from stdin (standard input), when creating
     an archive. Optional 'name' parameter allows to specify
     a file name of compressed stdin data in the created
     archive. If this parameter is missing, the name will be
     set to 'stdin'. This switch cannot be used with -v.

Why would I want to use RAR instead of GZIP? Well one thing GZIP doesn't have is the ability to automatically include a date stamp on the file name.

So with this info here is an example of how I will be backing up the MySQL database information:

mysqldump --all-databases | rar a -siWordPressDB.sql -ag_MMMDDYYYY-HHMM WordPressDB.sql.rar

Which creates an archive file that looks similar to the following name:

WordPressDB.sql_Feb242010-0938.rar

and contains a single file:

WordPressDB.sql

Pretty cool...

I think I would actually do this using find and then pass that input into tar. Using your example, let's assume you want files that are between 60 and 90s days old.

find /home/public_html/images -type f -daystart -mtime -90 -and -mtime +60 -print0 | xargs -0 tar -Ajf images_60-90.tar.bz2

This will list all the files that were last modified more than 60 days ago and less than 90 days ago and place those in the tarball named images_60-90.tar.bz2. My use of -print0 and xargs are mostly to protect yourself from files with spaces in the names, and in case there are so many files that they go over the command line maximum length (which can be found by running the command getconf ARG_MAX). I haven't tested that command, and I don't know what happens if you use the append option when the file doesn't exist, so you may have to do more tweaking.

If, however, you know that there are no spaces in any file names, and there will be fewer files than the value of ARG_MAX, you can simply your command a bit.

find /home/public_html/images -type f -daystart -mtime -90 -and -mtime +60 tar -cjf images_60-90.tar.bz2