Split and then join a file on linux - for email backup etc

On OSX terminal ssh to centos

Split:
split -b 25000000 -d httpdocs.tar.gz httpdocsgz
(gmail does not accept attachments over 25M)

Mail:
echo "site backup" | mutt -s "site backup0" -a httpdocsgz00 xyz@gmail.com
echo "site backup" | mutt -s "site backup0" -a httpdocsgz01 xyz@gmail.com
etc

Join back:
cat httpdocsgz* > httpdocs.tar.gz
(after downloading)