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  Something you may not know about Shell

Shell is also called command line interface, it is the interface between *nix users and computer. Shell is a program which provides service to access OS kernel services. This article is to introduce some not so well known but useful and interesting knowledge about shell. Wiki shell was born almost at the same time as Unix. The first UNIX shell was written by Ken Thompson in 1971 and its name is Thompson sh. It's older than Linux kernel. The default Shell in most *nix and MacOS is bash, bash was...

2,840 0 0          LINUX COMMAND SHELL UNIX


  Convert ext3 to ext4 file system on CentOS

ext3 is a journaled file system that is commonly used by the Linux kernel. It is the default file system for many popular Linux distributions, including Debian. Stephen Tweedie. On June 28, 2006, Theodore Ts'o, the principal developer of ext3, announced an enhanced version, called ext4. Today, we will show how to convert ext3 to ext4 format on CentOS. System environment: Release version : CentOS release 5.4(Final) Kernel:  Linux localhost.lo...

3,490 0 0          CENTOS EXT3 TO EXT4


  Use rsync to delete mass files quickly in Linux

Yesterday I encountered an issue to delete many log files in my Linux workstation, there were around 100,000 files to be deleted. These are log files and they grow very fast, and we need to delete them frequently. Usually we would use rm -rf * to delete these files, but we may need to wait for a relative long time if there are too many files. So we must adopt some unusual way. Fortunately, we can use rsync to delete mass files in one shot. 1. Install rsync yum install rsync 2. Create a new empty...

7,063 0 0          DEMO RSYNC DELETE FILE


  Concise bash programming skills

The following are some concise bash programming skills which we may need in our daily programming work. 1. Check status of command execution The usual way: echo abcdee | grep -q abcd   if [ $? -eq 0 ]; then echo "Found" else echo "Not found" fi Concise way: if echo abcdee | grep -q abc; then echo "Found" else echo "Not found" fi Of course you can remove if...else with following code [Sun Nov 04 05:58 AM] [kodango@devops] ~/workspace $ echo abcdee | grep -q ...

8,450 1 1          TIP BASH SKILL


  9 reasons to use Zsh

Like majority *nix users, I have been using bash for many years. Sometimes I feel uncomfortable with bash. I tried use some other shells as well such as ksh, tcsh and zsh which I am going to talk about. A few days ago, I found an open source project ranking in the 6th named oh-my-zsh on Github, I downloaded it and had a try with it. It's amazing. We should use zsh to replace bash now. Why do we need to use zsh? Here is a 4 minutes YouTube video which shows many reasons why we should switch from ...

5,015 0 0          ZSH ADVANTAGE COMMAND


  Using msmtp to replace sendmail

sendmail is a mail client in Linux with many vulnerabilities and tedius configuration steps, many system administrators have disabled using it. Then how do we know what happens if a crontab script executes with error? Actually there are some replacements for sendmail, one is ssmtp, but this application is no longer maintained, we even cannot find its source code on Google. Fortunately, we can use msmtp to replace sendmail. The address : http://msmtp.sourceforge.net/ 1. Installation After downloa...

4,770 0 0          SENDMAIL MSMTP REPLACEMENT


  Install Open webOS on Linux

HP has just released its first beta version of the webOS, It is said the user experience of webOS is quite impressive, so I immediately had it installed on my PC. There are two versions of Beta release,one embedded version and one Ubuntu version. I briefly share my installation experience of webOS in Linux. In the official document, it says "By 'Linux' we mean 'Ubuntu Linux'", it doesn't support server version and 64 bit version of Ubuntu. Here I use Mint 13. 1. Clone source code from github Add...

3,100 0 1          UBUNTU LINUX HP WEBOS EMBEDDED


  Understand diff in Unix

diff is an important tool program in Unix. It is used to compare differences of two files, it is the foundation for code version control. If you type : $ diff <file_before_change> <file_after_change> diff will tell you what's the difference between these two files. The result may not be so easy to understand, so now I will show you how to understand diff. 1. 3 formats of diff diff has 3 formats due to historic reasons. normal diff context diff unified diff 2. Demo files For easy d...

7,640 0 0          UNIX DIFF VERSION CONTROL GIT