switch

#!/bin/bash
#switch file1 for file2

file1=$1
file2=$2

if [ $# -ne 2 ]; then
  echo "usage: $0 file1 file2"
  exit 1
fi

if [ ! -e $file1 ]; then
  echo "Error: $file1 does not exist!"
  exit 2
fi

if [ ! -w $file1 ]; then
  echo "Error: $file1 is not writable!"
  exit 2
fi

if [ ! -e $file2 ]; then
  echo "Error: $file2 does not exist!"
  exit 2
fi

if [ ! -w $file2 ]; then
  echo "Error: $file2 is not writable!"
  exit 2
fi

mv $file1 ${file1}.temp
mv $file2 $file1
mv ${file1}.temp $file2