Use xmllint and vim to format xml documents

If you want vim to nicely format an XML file (and a xena file in this example, 2nd line) then add this to your ~/.vimrc file:
" Format *.xml and *.xena files by sending them to xmllint
au FileType xml exe ":silent 1,$!xmllint --format --recover - 2>/dev/null"
au FileType xena exe ":silent 1,$!xmllint --format --recover - 2>/dev/null"

This uses the xmllint command to format the xml file.. useful on xml docs that aren’t formatted in the file.