rpm2cpio xxx.rpm | cpio -div

例如：

rpm2cpio vim-8.2.2918-1.1.x86_64.rpm | cpio -div

直接scp加参数 -o "StrictHostKeyChecking no"

scp -o "StrictHostKeyChecking no" -i /root/key xxx.qcow2 192.168.1.100:/opt/vm/

文件系统挂了，变成只读模式。supervisor无法启动，就连ping 域名时无法解析dns，想要修改/etc/resolve.conf，只读也写不进去。
试下往临时目录写也是这：

touch /tmp/aaa.txt
touch: cannot touch '/tmp/aaa.txt': Read-only file system

You can use vim programmatically with the option -c {command} :

Dos to Unix:

vim file.txt -c "set ff=unix" -c ":wq"

Unix to dos:

vim file.txt -c "set ff=dos" -c ":wq"

"set ff=unix/dos" means change fileformat (ff) of the file to Unix/DOS end of line format

":wq" means write file to disk and quit the editor (allowing to use the command in a loop)

使用iptables进行端口转发，如下，需要访问原主机的27017端口，但是没开放，只开放了5000-6000之间的端口，因此 需要映射 一个5027端口去访问27017 这个mongodb。

iptables -t nat -A PREROUTING  -p tcp --dport 5027 -j DNAT --to-destination :27017

列表:

iptables -t nat --list

删除
PREROUTING 后跟的index 索引从1开始

iptables -t nat --delete PREROUTING 2

Things like this:

It brings useless word when we copy and paste the output.
To avoid this, we can use setTimeout with a console.log.bind:

setTimeout (console.log.bind (console, "This is a sentence."));

It's clean now!

Simply as

wget -i url.txt

url.txt is multple urls in each line. Like this:

https://ss3.bdstatic.com/70cFv8Sh_Q1YnxGkpoWK1HF6hhy/it/u=3302399998,3216746631&fm=26&gp=0.jpg
https://ss2.bdstatic.com/70cFvnSh_Q1YnxGkpoWK1HF6hhy/it/u=1588620919,359805583&fm=26&gp=0.jpg

BTW, it's very fast.

for x in {a..z}
do
    echo "$x"
    mkdir -p path2/${x}
    mv path1/${x}*.ext path2/${x}
done

One line with upper case example:

for letter in {A..Z} ; do wget http://www.abc.com/Letter_${letter}_Cap.gif;done;

bash中如何实现条件判断？
条件测试类型：

• 整数测试
• 字符测试
• 文件测试

在Linux，你是不是曾经天真的以为，使用rm删除一个文件，占用的空间就释放了？事情可能不是常常如人意。