Likely, you did not make the script executable. Like
chmod +x build_coreboot.sh
or see Building coreboot from source (official script) - #4 by deadsuperhero, post #4
Likely, you did not make the script executable. Like
chmod +x build_coreboot.sh
or see Building coreboot from source (official script) - #4 by deadsuperhero, post #4