Question

3、编写一个Shell脚本，从键盘上接收两个文件名，如果两个文件都存在则交换两个文件的内容，否则应给出出

Answer 1

下面是代码
#!/bin/bash

if [ -z $1 ]; then
echo "Input file 1 and file 2"
exit
fi

if [ -z $2 ]; then
echo "Input file 2"
exit
fi

if [ ! -f $1 ]; then
echo "$1 doesn't exist."
exit
fi

if [ ! -f $2 ]; then
echo "$2 doesn't exist."
exit
fi

mv $1 /tmp/diff.tmp
mv $2 $1
mv /tmp/diff.tmp $2
rm -rf /tmp/diff.tmp

echo "Finished change file"

下面是运行结果
[wyc@wyc-desktop:bash]$ echo 1.c > 1.c
[wyc@wyc-desktop:bash]$ echo 2.c > 2.c
[wyc@wyc-desktop:bash]$ cat 1.c
1.c
[wyc@wyc-desktop:bash]$ cat 2.c
2.c
[wyc@wyc-desktop:bash]$ ./diff.sh 1.c 2.c
Finished change file
[wyc@wyc-desktop:bash]$ cat 1.c
2.c
[wyc@wyc-desktop:bash]$ cat 2.c
1.c