In https://access.redhat.com/documentation/en-us/assisted_installer_for_openshift_container_platform/2024/html/installing_openshift_container_platform_with_the_assisted_installer/assembly_booting-hosts-with-the-discovery-image#booting-hosts-using-ipxe_booting-hosts-with-the-discovery-image

The instruction for using iPXE have CLI arguments like: 

$ awk '/^initrd /{print $NF}' ipxe-script | curl -o initrd.img

In step 2i and 2ii. In these situations, I believe it requires xargs. Additionally, it may benefit from -L for forwarding if the resource has been moved elsewhere. The following worked for me:

$ awk '/^initrd /{print $NF}' ipxe-script | xargs curl -o initrd.img -L

The following also worked: 

$ awk '/^kernel /{print $2}' ipxe-script | xargs curl -o kernel -L

Lastly, this worked too:

$ grep ^kernel ipxe-script | xargs n1| grep ^coreos.live.rootfs_url | cut -d = -f 2 | xargs curl -o rootfs.img -L