[CentOS] backups and md5 all in one while splitting

Ross S. W. Walker rwalker at medallion.com
Mon Nov 12 22:54:05 UTC 2007


'tee' splits the stdin into multiple output streams.

The first instance of tee you listed gave it a file name and a pipe to output the stdout to.

The second instance did a redirection to a sub-shell which then passed it to 'split' and it also had a pipe.

-Ross


-----Original Message-----
From: centos-bounces at centos.org <centos-bounces at centos.org>
To: CentOS mailing list <centos at centos.org>
Sent: Mon Nov 12 17:44:47 2007
Subject: Re: [CentOS] backups and md5 all in one while splitting

Shad L. Lords wrote:
>> I'm trying to back up our svn repositories, and I found a nice little 
>> backup command line bzip's the backup and creates the md5 hash all in 
>> one:
>>
>> svnadmin dump --deltas /repo |bzip2 |tee dump.bz2 | md5sum >dump.md5
>>
>> The problem is I need to split the backups, so this doesn't really 
>> work. Is there perhaps another way of piping things to allow for 
>> splitting of the backups?  Currently I'm doing something like this
>>
>> svnadmin dump --deltas /repo |bzip2 |split - -b 64m
>> cat *.bz2* | md5sum >dump.md5
>>
>> Is there a way to do this all in one step?
>
> What about:
>
> svnadmin dump --deltas /repo | bzip2 | tee >(split -b 64m - dump.bz2.) 
> | md5sum > dump.md5
>
> -Shad
> _______________________________________________
> CentOS mailing list
> CentOS at centos.org
> http://lists.centos.org/mailman/listinfo/centos

This seems to work well, but I have no idea what it's doing.  Can 
someone walk me through what
tee >(split -b 64m - dump.bz2.) does and why?

Russ


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