dd if=/dev/zero bs=1M count=100 | tr '\000' '\377' > file
Source: https://www.linuxquestions.org/questions/linux-software-2/writing-0xff-with-the-dd-command-845232/
dd if=/dev/zero bs=1M count=100 | tr '\000' '\377' > file
Source: https://www.linuxquestions.org/questions/linux-software-2/writing-0xff-with-the-dd-command-845232/