Ubuntu – What’s the difference between mkfs and mkdosfs

I think you see killall in how-to's because by default it requires the precise process name, whereas pkill does basic pattern matching. Thus, killall is safer for users to blindly copy and paste.

Pkill and killall both have distinguishing options. Killall has a flag to match by process age, pkill has a flag to only kill processes on a given tty. Etcetera ad nauseum. Neither is better, they just have different specialties.

I see from their man pages that killall comes from the psmisc package, which has several process managing utilities, but notably doesn't contain ps. It's the procps package that has ps, top, kill, and pkill (among others). I'd wager procps didn't originally have pkill, so psmisc scratched an itch and came up with killall.

The pkill/pgrep man page says they were introduced in Solaris 7. As you mention, jgbelacqua, Solaris's killall was not the utility psmisc provides, thus Solaris probably only had the procps package. Someone wanted a pattern matching process tool, thus pkill and pgrep. Whether it was developed by the procps dev or added in afterwards, I don't know. Regardless, it made it in and became part of *nixes everywhere.

More sources:

• http://www.freebsdsoftware.org/sysutils/linux-procps.html
• http://www.freebsdsoftware.org/sysutils/psmisc.html
• http://procps.sourceforge.net/faq.html
• OpenSolaris (now Illumos) source code for ps, at launch in 2005

fdisk manages partitions, but does not format or write data to the disk.

To format the disk, use mkfs

# FAT
mkfs.vfat /dev/sdxy # /dev/sdxy is your usb

# Or for ext4
mkfs.ext4 /dev/sdxy 

However, formatting does not overwrite your data, it just removes the pointers to where it is. To overwrite your data you actually need to write over it, use dd or a utility such as scrub

scrub /dev/sdxy

See also man scrub