Shortest way to swap two files in bash

Question

Can two files be swapped in bash?

Or, can they be swapped in a shorter way than this:

cp old tmp cp curr old cp tmp curr rm tmp 

Answer 1

$ mv old tmp && mv curr old && mv tmp curr 

is slightly more efficient!

Wrapped into reusable shell function:

function swap()          {     local TMPFILE=tmp.$$     mv "$1" $TMPFILE && mv "$2" "$1" && mv $TMPFILE "$2" } 

Answer 2

Add this to your .bashrc:

function swap()          {     local TMPFILE=tmp.$$     mv "$1" $TMPFILE     mv "$2" "$1"     mv $TMPFILE "$2" } 

If you want to handle potential failure of intermediate mv operations, check Can Bal's answer.

Please note that neither this, nor other answers provide an atomic solution, because it's impossible to implement such using Linux syscalls and/or popular Linux filesystems. For Darwin kernel, check exchangedata syscall.