Quick Tip: How to rebuild all initrds with dracut in CentOS 6/7

If you need to automatically rebuild all initrds for all installed kernels:

rpm -qa | grep kernel | grep -v headers | grep -v tools | sed 's/^kernel\-//g' | xargs -i dracut -v -f /boot/initramfs-{}.img {}

Oh, and while we're at it, the same for Ubuntu

update-initramfs -u -k all