Code

Understanding the file structure of wav

Usually we use data[44:] to eliminate the header information of wav files, and then assume the rest data is PCM. This may not always be true. For the wav header of a PCMWAVEFORMAT, we can usually understand that a structure as follows is at the front, and then followed by Read more…

By Yu, 3 years2 years ago

Code

Boot from grub in CentOS 7

After my CentOS 7 upgrade, I rebooted it. It gets stuck and shows a prompt like this:

grub >

It is an annoying start.

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By Yu, 3 years2 years ago

Code

gflags: helpshort in default

gflags is a simple argument parser in C++, we use it to parse the args.

When you use --help and trying to print a help message, it will burst out a lot of useless flags.

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By Yu, 3 years2 years ago

Code

Lazy Initialize Data Attributes in Python

Suppose we want to create a “lazy” data attributes ( “instance variables” in Smalltalk, or “data members” in C++) in a Python Class. We may required to use getattr to customize attribute access.

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By Yu, 3 years2 years ago

Code

Avoid stuck after ‘SSH2_MSG_SERVICE_ACCEPT received’

It is becoming pretty slow in SSH to a CentOS server.

Trying to print a verbose log:

$ ssh -vvvv my-host
....
debug3: send packet: type 21
debug2: set_newkeys: mode 1
debug1: rekey out after 134217728 blocks
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug3: receive packet: type 21
debug1: SSH2_MSG_NEWKEYS received
debug2: set_newkeys: mode 0
debug1: rekey in after 134217728 blocks
debug1: Will attempt key: /Users/user/.ssh/id_rsa RSA SHA256:XXXXX/gNY explicit
debug2: pubkey_prepare: done
debug3: send packet: type 5
debug3: receive packet: type 7
debug1: SSH2_MSG_EXT_INFO received
debug1: kex_input_ext_info: server-sig-algs=
debug3: receive packet: type 6
debug2: service_accept: ssh-userauth
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug3: send packet: type 50
..... <<<-- long long long silence here
debug3: receive packet: type 51 <<<-- and then continue to access the server
debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password
debug3: start over, passed a different list publickey,gssapi-keyex,gssapi-with-mic,password
debug3: preferred publickey,keyboard-interactive,password

(more…)

By Yu, 3 years2 years ago

Code

防止 Ubuntu 自动待机

Ubuntu 如果插上显示器不使用，一段时间（通常是 20 分钟）后会突然停了。

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By Yu, 4 years4 days ago

Code

从源码编译 golang

首先下载 golang 的代码，可以从 https://golang.org/dl 或者中国的 mirror https://golang.google.cn/dl 下载最新的 go<version>.src.tar.gz. 然后开始编译就可以。

构建方法基本可以参考官方文档就可以。

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By Yu, 4 years2 years ago

Code

Initialize Jetson Nano Environment

If we use Jetson Nano‘s default image to start our project, we may have some follow steps to make our work easier.

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By Yu, 4 years2 years ago

Code

Go Proxy Configurations

To speed up our dependencies updating for golang, or prepare some patterns for our special libraries, we probably consider to use a proxy to speed it up.

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By Yu, 6 years2 years ago

Code

The short-circuiting in bash

Bash script writing is a import approach to configure the linux system. Suppose we wish to add a user if not exists, the command may seems as follow:

TARGET_USER=alice
if (! id -u $TARGET_USER > /dev/null 2>&1 ); then
    echo "creating user $TARGET_USER"
    # adduser $TARGET_USER
fi

However, it is kind of too long. In this case short-circuiting is a alternative solution. (more…)

By Yu, 6 years2 years ago

Code

A simple workflow to create a clean python library based on Anaconda

The open-source Anaconda Distribution is an easy way to perform Python/R data science and machine learning on Linux, Windows, and Mac OS X. We could easily prepare an isolated and constant environment on anywhere based on a configure file.

Considering the various kind of strange errors due to the different versions of python and python libraries, this management tool makes our life much more comfortable in deploying and cooperating.

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By Yu, 6 years2 years ago