Terminal: create bootable USB from iso

Using gparted remove the existing partitions from your usb, and fix the msdos partition table (by going to the device menu and selecting "create partition Table"). Then, create a new partition fat32 by right clicking on the unallocated space and selecting new, making a primary FAT32 partition.

Next step create your bootable usb:

dd if=/path_to_iso_without_space.iso of=/dev/sdx
sync

You can add the bs=4M option to make it faster:

dd bs=4M if=/path_to_iso.iso of=/dev/sdx

Example: if your device is sdb1 you should type sdb

dd if=/path_to_iso_without_space.iso of=/dev/sdb

If it is a archlinux bootable iso, you don't have to do anything special. Just

dd if=somefile.iso of=/dev/sdx

where sdx is the block device like /dev/sda and not a partition like /dev/sda1.

This is possible as the iso already contains all that is needed. If you set some partition table, it will simply has no effect, as it will be overriden by dd, as anything else on the target device.

Edit: You sure have to unmout any partition on that device, as they will be overriden as described before.

Edit2: The same applies to the manjaro image, according to their wiki.

If you don't know your USB device block file (such as /dev/sdb) and if you want to make sure you're not writing over one of your sata system drives, you can use the more secure bootiso utility.

You can give your USB device name explicitly (will fail if it is not connected through USB):

bootiso -d /dev/sdb /path_to_iso_without_space.iso

Or let him find it for you:

bootiso /path_to_iso_without_space.iso

See it in action: