替换一个目录下文件中的某一字符串

例如替换目录中所有*.html文件中的"test"为"test123".

代码如下:
#!/bin/sh
#replace_string.sh - replace string in files under the same directory
#Example Usage: ./replace_sting.sh "*.html" test test123
#Author: Kevin Zhou
#Date: 2006/4/13

usage()
{
        echo "./replace_string \"file_type\" src_string dst_string"
        echo "Exapmle: ./replace_string \"*\" test test123"
        exit
}

if [ -z $2 ]; then
        usage
fi

if [ -z $3 ]; then
        usage
fi

for f in $1; do
        echo "sed s/$2/$3/ $f > $f.bak"
        echo "mv -f $f.bak $f"
done