Bash commands not working after SFTP script
EOF is not at the beginning of the line. Changing your script to:
#!/bin/sh
sftp -b /dev/stdin server <<EOF
cd /shares/backup/webserver/
put $bu_PATH$BACKUP_FILE
quit
EOF
echo "Backup done"
should make it work.
You might replace /dev/stdin server by - as the latter means stdin.