与其说是对博客的规划，倒不如是说对我最近紊乱生活的梳理。漫无目的会让人疲惫，前一阵子我累得走也不动，站也不直。糟乱之下，自然不会做一些轻松愉快的事情。现在让我最头疼的是注意力涣散，还有拖延的毛病。
话说对个人来说，长效的改变都是一点一滴开始的，晨练从几日前开始了，吃灰的哑铃擦干净放到了门边，清晨喝水尚未落实到位，前几天删了几个博客分类，在 spirit 和 life 之间犹豫许久，最后认为信仰、神话与宗教掺杂的精神世界也是生活的一部分，遂保留了后者。
常常说起时间不够用，其实是把时间花费在了发呆，刷推，喝汤，听歌，看视频上，娱乐在正常生活所占的地位的确重要，但不仅仅是我，更多人用一种只会使自己更加疲惫、而非让精神愈发充沛的方式去娱乐。往往在电脑手机的信息冲刷下精疲力尽，累得发困，还怎么继续充实地生活工作学习呢？
有时候很渴，渴得让我烦躁，却懒得去接一杯水；有时候憋尿，千钧一发，岌岌可危，非要做完手头的事情才去厕所。现在感觉这跟自己过不去的做法是个笑话，但又那么真实、对我来讲理由充分。
Last Update: 2019-09-10
Functions: changing the mac address and hostname for each boot.
Tip: The example code is on Debian.
The macchanger (a.k.a., the GNU MAC Changer) provides a variety of features such as changing the address to match a certain vendor or completely randomizing it.
Install the package macchanger from the official repositories.
1 | sudo apt update |
Display available network interfaces.
1 | ip a |
Change the mac address:
1 | sudo macchanger -r your_interface_name |
如果你想要同时验证下载文件的可靠性（拥有者）和完整性（内容），你需要依赖于加密签名。本教程中，将描述如何使用 GnuPG（GNU Privacy Guard）来检查文件的可靠性和完整性。
本例中将验证一个从 https://opensuse.org 上下载的磁盘镜像。这个网站中，发行商会提供他们的公钥，还有它用于密钥验证的指纹。
至于下载的文件，发行商提供它了相关的利用 GPG 签名的含有 sha256 校验值的文件。
在 Debian、Ubuntu 和其他 Debian 衍生版上：
1 | sudo apt install gpg |
在 Fedora、CentOS 或者 RHEL 上:
1 | sudo yum install gnupg |
完成安装后，生成一个键对。
在生成键对期间，用户会被要求提供姓名和 email，还有保护私钥的密码。用户同样也可以选择键对何时过期（默认不会过期）。依赖于用户选择的 key 的大小（在 1024 和 4096 位之间），key 生成会花上几分钟或者更多，同时它要求收集来自你桌面活动的大量的随机数据。（比如键盘输入、鼠标移动、磁盘访问等等，所以这个时候随便动动鼠标键盘什么的）。
一旦 key 生成完毕后，公钥和私钥会存储在 ~/.gnupg 目录。
Tips: This is my homework of “Computer Control System” course, so mistakes do happen.
This article will discuss an interpolation algorithms for line and circular. And it provides an implement of C language.
Many numerical control machines are powered by stepping motors. When a pulse is sent to a stepping motor, the stepping motor alters its position by a unit step. Two motors can be used to control the XY movements of an arm or tool over a working plane.
If the pulse are generated by a device which can remember or generate a specified train of pulses, repetitive operations such as grinding, painting, or cutting can be performed hunderds of times with virtually no variation. A microcomputer is an obvious choice to gernerate and remember the pulse.
Since stepper motors can move only in discrete steps, we must approximate the actual curve by a series of small XY motions. Many algorithms rely upon parametric functions such as sine and cosine to perform the necessary calculations. Parametric functions, however, typically require a high degree of numeric precision. Calculating sine and cosine values with a microcomputer can be too time-consuming to be useful in a realtime application.
The following two algorithms require no parametric functions. This makes them ideally suited to the
computation and memory capacities of microcomputers. Since these algorithms do not require a large amount of complex mathematical calculation, they are fast enough to be used in real-time applications.