Kelvin's tech-box

Topic

linux

A collection of 29 issues

What does 2>&1 mean in linux shell

In a unix shell, if I want to combine stderr and stdout into the stdout stream for further manipulation, I can append the following on the end of my command: 2>&1 File descriptor 1 is the standard output (stdout). File descriptor 2 is the standard error (stderr)

Setup the vagrant as dev environment

$ sudo adduser kelvin copy the ssh keys copy the public key to ~/.ssh/authorized_keys change the ssh.username to kelvin bzr lp-login kelvin.li add the user to sudo $ sudo adduser <username> sudo $ sudo vim /etc/sudoers add kelvin ALL=(ALL) NOPASSWD: ALL Remove Existing User from

Useful shell

check the keyword in response header $ curl -vvvsH "Host: software-center.ubuntu.com" -H "Accept-Encoding: gzip" http://91.189.89.82/api/2.0/applications/en/ubuntu/precise/i386/ 2>&1 > /dev/null | grep 'ETag\|X-Cache\|Content-Length\|Content-Type' kill the pid of

IRC client IRSSI setup

I use IRC on remote server more and more frequently, in case I need to config this in the future, the regarding setup steps are consolidated here. Install $ sudo apt install irssi Start by: screen irssi Hilight Window Put the script in ~/.irssi/scripts/autorun/ and type /run autorun/hilightwin.

Ubuntu 增加Swap的空间

新安装了ubuntu，但是忘记了规划swap分区。或者swap分区太小，想要增大些，其实这些任务在linux下都是十分简单和方便实现的。新增分区使用一个文件来实现此功能。 1. 建立一个img文件，大小为512M，需要1024的话就把count=500000改成1000000，这样我们才能访问它。 dd if=/dev/zero of=swap.img bs=1024 count=500000 2. 进行格式化 mkswap swap.img 3. 当然是激活它，使它可用。 sudo swapon swap.img 增大分区 1. 首先用命令free查看系统内 Swap 分区大小。 free -m total used free shared buffers cached Mem:

How to create Ubuntu startup disk on Mac

1. Create dmg file from iso hdiutil convert -format UDRW -o /tmp/ubuntu-14.04.1-server-amd64.img /Users/kelvin/Downloads/ubuntu-14.04.1-server-amd64.iso 2. amount the disk diskutil unmountDisk /dev/disk2 3. copy the disk sudo dd if=/tmp/ubuntu-14.04.1-server-amd64.img.dmg of=/dev/rdisk2 bs=1m 4.

JuJu explore

Develop once, Running everyone in the Cloud. SOA:This is a great implementation for the Service Orientation Architecture.As a developer, from my point of view, it could reduce me a lot of efforts and time for the deployment by using Charms which could be developed by some experts. EX:

VNC setup on linux

I need to connect to the Ubuntu desktop from Mac machine, a vnc service is needed. Install apt-get install vnc4server $vncpasswd VNC Start with the different resolution $vnc4server --geometry 1440x900 :1 $vnc4server --geometry 1600x1200 :2 VNC Stop $vnc4server -kil :1 Configuration file emacs ~/.vnc/xstartup #!/bin/sh # Uncomment the following

Create the lowest permission SSH user account

#create user useradd -M -s /sbin/nologin -n username #modify the password passwd username #remove the user userdel -r username

How to setup a HTTPS site

Recently I am going to use SSL on my site. Some important steps were record here for your information. Generate CSR (Certificate Signing Request) $ openssl genrsa -out domain.key 2048 $ openssl req -new -key domain.key -out domain.csr Remove the key's password $ openssl rsa -in memodir.key