Programming is the art of adding bugs to an empty text file

Louis Srygley:

Without requirements or design, programming is the art of adding bugs to an empty text file.

Vim folding

  • zi - toggle folding
  • za - toggle current fold open/close
  • zR - open all folds
  • zM - close all folds
  • zc - close current fold

  • zo - open currrent fold

  • zj - move down to next fold
  • zk - move up to previous fold
nnoremap <Space> za

在所有子目录下执行 git

git config --global alias.all '!f() { ls -R -d */.git | sed 's,\/.git,,' | xargs -P10 -I{} git -C {} $1; }; f'

git all pull

8 Years in Beijing

8.

setlock

setlock - runs another program with a file locked.

setlock [-nNxX] fn child，简单说 setlock 会打开 fn 并加锁，然后执行 child。如果 lock 失败，可以指定 child 退出或等待：

-n: fn 被其他进程锁住，setlock 放弃执行 child
-N: fn 被其他进程锁住，setlock 会等待，直到重新加锁，并执行 child
-x: fn 打开失败或已加锁，setlock exit 0
-X: fn 打开失败或已加锁，setlock 输出错误并退出

setlock 可以和 crontab 搭配使用，比如某个任务每十分钟执行一次，如果上一次执行尚未退出，不再开启新任务:

*/10 * * * * /usr/bin/setlock -n /tmp/test.lock /home/x.sh

Stop

Stop, 是一个行程的中止。

Stop，也是一个站点，下车，上车，继续前进。

2010.6 - 2018.5.

Nginx + Websocket

upstream ws {
    server 127.0.0.1:8080;
    server 127.0.0.1:8081;
}

server {
    listen  8090;

    location / {
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "upgrade";

        proxy_pass http://ws;
    }
}

在 Nginx reload 的时候，socket 连接并不会中断。

Quote

什么都不放弃实际上是怕放弃后自己什么都没有，无所畏惧的人生要敢于放弃。

via

Linux Performance Analysis in 60s

uptime/w --------------------> load average
dmesg | tail ----------------> kernel errors
vmstat 1 --------------------> overall stats every second
mpstat -P ALL 1 -------------> CPU balance
pidstat 1 -------------------> process usage, every second
iostat -xz 1 ----------------> disk I/O
free -m ---------------------> memory usage
sar -n DEV 1 ----------------> network I/O
sar -n TCP,ETCP 1 -----------> TCP stats
top -------------------------> check overview

dmidecode

You can use dmidecode to display server physical info, for example RAM max capacity.

dmidecode -t 16

Handle 0x0032, DMI type 16, 15 bytes
Physical Memory Array
	Location: System Board Or Motherboard
	Use: System Memory
	Error Correction Type: Multi-bit ECC
	Maximum Capacity: 48 GB
	Error Information Handle: Not Provided
	Number Of Devices: 6