Linux 10 read_linux 磁盘硬件 read10-优快云博客

本文链接：https://blog.youkuaiyun.com/zhengdongchao/article/details/6496006

本文展示了如何使用read命令从标准输入读取数据，并将其分配给变量进行文件操作，包括复制文件、检查文件是否存在及覆盖选项。

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read
read variables
从标准输入读入一行数据，并把所读入的第一个词赋给variables中列出的第一个变量，第二个赋给第二个变量。。。。
[donggua@donggua-desktop:~]$ cat mycp
#copy a file
if [ "$#" -ne 2 ]
then
   echo "usage:mycp from to"
   exit 1
fi
from "$1"
to="$2"
if [ -e "$to" ]
then
   echo "$to already exit,overwrite(yes/no)?"/
   read answer
   if [ "$answer"!=yes ]
   then
    echo "copy not performed"
    exit 0
   fi
fi
cp $from $to
[donggua@donggua-desktop:~]$ ./mycp
usage:mycp from to
$$当前进程的ID号
[donggua@donggua-desktop:~]$ grep -v "google" express.txt>/tmp/express.txt
[donggua@donggua-desktop:~]$ mv /tmp/express.txt express.txt
mv：是否覆盖“express.txt”?
[donggua@donggua-desktop:~]$ grep -v "google" express.txt>/tmp/express.txt$$
[donggua@donggua-desktop:~]$ mv /tmp/express.txt$$ express.txt
mv：是否覆盖“express.txt”?
[donggua@donggua-desktop:~]$ cat addi
while read n1 n2
do
echo $((n1+n2))
done
[donggua@donggua-desktop:~]$ ./addi <two>sums