find dir | xargs grep str # dir是指某个目录
find file | xargs grep str # file是指某个文件2.

grep str dir/* # dir是指某个目录，但不递归搜索其子目录
grep -r str dir/* #使用-r选项，递归搜索其子目录
grep str file #file是指某个文件

#!/bin/bash
#find_str.sh
if [ $# -lt "2" ]; then
echo "Usage: `basename $0` path name [option]"
exit 1
fi
#!-r表示递归处理子目录,-i表示忽略大小写
path=$1
name=$2
shift
shift
for option in "$@"
do
case $option in
-r) dir_op="-r"
;;
-i) lu_op="-i"
;;
*) if [ -n "$option" ]; then
echo "invalid option"
exit 1
fi
;;
esac
done
grep_str_of_file()
{
file=$1
str=$2
out=$(grep -n $lu_op "$str" "$file")
if [ -n "$out" -a "$file" != "$0" ]; then
echo "$file: $out"
fi
}
find_str()
{
if [ -d "$1" ]; then
for file in $1/*
do
if [ "$dir_op" = "-r" -a -d "$file" ]; then
find_str $file $2
elif [ -f "$file" ]; then
grep_str_of_file $file $2
fi
done
elif [ -f "$1" ]; then
grep_str_of_file $1 $2
fi
}

$ find_str $path $name