Recover svn repository
It is normal that svn db get crashed because of permission issue. The following steps help to fix it.
chown svnuser:svngroup /path/to/repos
find /path/to/repos -type d -print0 -exec chmod 2775 {} \;
find /path/to/repos -type f -print0 -exec chmod 0664 {} \;
svnadmin recover /path/to/repos
Vi Editor magics
Adding line number to a file with vi
open the file with vi editor
:%!nl
of-course there are other ways to do it with vi 
Add empty line after every line with vi
:%s/\v(.*\n){1}/&\r
Remove white space at the beginning of a line with vi
:%le
Sorting lines with vi
:sort u
