linux 清空文件

Posted 2020-11-19 烈火延维

将Linux文件清空的几种方法
1、使用重定向的方法

[[email protected] ~]# du -h test.txt 
4.0K    test.txt
[[email protected] ~]# > test.txt 
[[email protected] ~]# du -h test.txt 
0    test.txt

2、使用true命令重定向清空文件

[[email protected] ~]# du -h test.txt 
4.0K    test.txt
[[email protected] ~]# true > test.txt 
[[email protected] ~]# du -h test.txt 
0    test.txt

3、使用cat/cp/dd命令及/dev/null设备来清空文件

[[email protected] ~]# du -h test.txt 
4.0K    test.txt
[[email protected] ~]# cat /dev/null >  test.txt 
[[email protected] ~]# du -h test.txt 
0    test.txt
###################################################
[[email protected] ~]# echo "Hello World" > test.txt 
[[email protected] ~]# du -h test.txt 
4.0K    test.txt
[[email protected] ~]# cp /dev/null test.txt 
cp：是否覆盖"test.txt"？ y
[[email protected] ~]# du -h test.txt 
0    test.txt
##################################################
[[email protected] ~]# echo "Hello World" > test.txt 
[[email protected] ~]# du -h test.txt 
4.0K    test.txt
[[email protected] ~]# dd if=/dev/null of=test.txt 
记录了0+0 的读入
记录了0+0 的写出
0字节(0 B)已复制，0.000266781 秒，0.0 kB/秒
[[email protected] ~]# du -h test.txt 
0    test.txt

4、使用echo命令清空文件

[[email protected] ~]# echo "Hello World" > test.txt 
[[email protected] ~]# du -h test.txt 
4.0K    test.txt
[[email protected] ~]# echo -n "" > test.txt    ==>要加上"-n"参数，默认情况下会"
"，也就是回车符
[[email protected] ~]# du -h test.txt  
0    test.txt

5、使用truncate命令清空文件

[[email protected] ~]# du -h test.txt 
4.0K    test.txt
[[email protected] ~]# truncate -s 0 test.txt   -s参数用来设定文件的大小，清空文件，就设定为0；
[[email protected] ~]# du -h test.txt 
0    test.txt