交换两个文件

swap

#!/bin/sh

if [[ $# != 2 && $# != 3 ]]  
then
    echo '需要至少两个参数' >&2
    echo 'usage:'
    echo "$(basename $0) file1 file2 tmpdir" >&2
    exit 1
fi

FILENAME=$(date +%Y%m%d%H%M%S)_$$
tmpdir=/tmp
if [[ $# == 3 ]]  
then
    tmpdir=$3
fi

mv $1 $tmpdir/$FILENAME  && mv $2 $1 && mv $tmpdir/$FILENAME $2 || exit 1