#!/bin/bash
if [ $# -lt 1 ];then
echo "Usage:$0 + filepath"
exit
fi #判断用户是否输入了参数
match=$1 #将要查的文件赋值给变量match
found=0 #定义一个初始变量作为发生条件，当文件找到时对此变量重新赋值
for file in /etc/* #对目录进行遍历
do
if [ $file == $match ];then #判断文件是否匹配
echo "the file $match was found!"
found=1 #当文件匹配时，对初始变量重新赋值
break #文件找到后跳出循环
fi
done
[ $found -ne 1 ] echo "the file $match is not in /etc directory." #做最终的判断，文件未找到时found仍然是0，判断条件成立，输出文件未找到；当文件找到时，found被赋值为1，条件不成立，不做输出。
示例2：对脚本做修改，让用户自定义要查找的文件以及在那个目录下查找
#!/bin/bash
if [ $# -lt 2 ];then
echo "Usage:$0 + filepath + directorypath"
exit
fi
match=$1
found=0
for file in ${2}* #在位置参数2，用户给定的目录中(一层目录)遍历所有文件
do
if [ $file == $match ];then
echo "the file $match was found!"
found=1
break
fi
done
[ $found -ne 1 ] echo "the file $match is not in /etc directory."
