i figured it out:
Login to xwiki
curl -k -b cookies.txt -c cookies.txt -d
“j_username=xwiki_backup_user &j_password= xwiki_backup_user_password
&j_rememberme=true&submit=Log-in” “https:// xwiki_backup_server
:443/xwiki/bin/loginsubmit/XWiki/XWikiLogin”
download the xar:
curl -k --output "xwiki_backup_file "
-b cookies.txt -c cookies.txt "https:// xwiki_backup_server
/xwiki/bin/export/Space/Page?format=xar&pages=xwiki_backup_page "