external hard drive question

will i be able to install an operating system such as linux on an external hard drive and use it using my macbook pro?. or its impossible in general

Linux can be installed on external drive but make sure you create swap space on the local drive.... the amount of writes to the swap space have chances of reducing the life of the external drive if swap space is also created on the external drive.

do you mean that i should make a swap space on the internal hard drive or in the external hard drive.