Shortest way to swap two files in bash

$ 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"
}

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.

tmpfile=$(mktemp $(dirname "$file1")/XXXXXX)
mv "$file1" "$tmpfile"
mv "$file2" "$file1"
mv "$tmpfile" "$file2"

do you actually want to swap them? i think its worth to mention that you can automatically backup overwritten file with mv:

mv new old -b

you'll get:

old and old~

if you'd like to have

old and old.old

you can use -S to change ~ to your custom suffix

mv new old -b -S .old
ls
old old.old

using this approach you can actually swap them faster, using only 2 mv:

mv new old -b && mv old~ new

You could simply move them, instead of making a copy.

#!/bin/sh
# Created by Wojtek Jamrozy (www.wojtekrj.net)
mv $1 cop_$1
mv $2 $1
mv cop_$1 $2

http://www.wojtekrj.net/2008/08/bash-script-to-swap-contents-of-files/

using mv means you have one fewer operations, no need for the final rm, also mv is only changing directory entries so you are not using extra disk space for the copy.

Temptationh then is to implementat a shell function swap() or some such. If you do be extremly careful to check error codes. Could be horribly destructive. Also need to check for pre-existing tmp file.

Surely mv instead of cp?

mv old tmp
mv curr old
mv tmp curr