grep is excellent to match patterns from STDOUT/text files in command line or scripts. It’s handy. Sometimes, our problem is more complex than finding a keyword from a file. On a first thought, it may sound impossible using grep for such complex problems. But grep can be quite powerful than we thought. Today, let’s check
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Author: Eric Ma
Eric is a systems guy. Eric is interested in building high-performance and scalable distributed systems and related technologies. The views or opinions expressed here are solely Eric's own and do not necessarily represent those of any third parties.How to Install Go 1.13.x on Ubuntu 18.04
Posted onIn Ubuntu 18.04 LTS, the default Go lang version is 1.10. For compatibility reason, the Ubuntu LTS will usually keep the major release version numbers for packages. However, many applications, such as Hyperledger Fabric 2.0, require a newer version of Go. In this post, let’s take a look at how to install a system level
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GCC May “Save” You Some Recursive Functions Calls: an Analysis of a Function Call Stack Length Example
Posted onWe know compilers like gcc can do lots smart optimization to make the program run faster. Regarding functions call optimization, gcc can do tail-call elimination to save the cost of allocating a new stack frame, and tail recursion elimination to turn a recursive function to non-recursive iterative one. gcc can even transform some recursive functions
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Bash Learning Materials
Posted onBash (GNU Bourne-Again SHell) the default shell for many Linux distributions. It is very common for scripting languages in Linux. Bash is easy and straightforward for writing small tools. However, as most tools, it has its grammars that could easily cause bugs if they are not used correctly. Here I summarize a list of good
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How to Install Wine 32-bit on CentOS 8
Posted onSince version 7, RHEL and CentOS only have 64 bit versions. For some reasons, it’s better to run many Windows applications under 32 bit wine. Like How to Install Wine 32-bit on CentOS 7, this post introduce how to install 32-bit Wine on CentOS 8. Most of the mechanisms are similar yet there are differences.
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How to Convert Integers to Strings and Strings to Integers in PHP
Posted onConversion from integer to string and from string to integer are common operations in most applications such as C++. PHP has its uniqueness in language and standard library design. In this post, we will check methods to convert integers to strings and vice versa. Convert string to int in PHP You can cast a string
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Synchronizing Thunderbird Calendar and Address Book with Office365 Exchange Online using ActiveSync
Posted onThunderbird is a nice email client available on Linux and Windows. With the Lightning plugin, Thunderbird can support calendar functions well. Exchange is a widely used email and calendar/address book service software. Office 365 provide the cloud version of Exchange named Office 365 Exchange Online. Although Exchange Online provide IMAP for synchronizing emails, it provides
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How to Make iPhone with iOS 13 Faster
Posted onAfter the recent iOS upgrading to version 13, many older iPhones such as iPhone 8 turn to be running slower, although there are many new features. New features and functions use more CPU/GPU/memory and the iOS may run slower. But are there any methods to make it run faster? After quite some research and testing,
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How to Change Windows User Name on Windows 10 Using Computer Management
Posted onThe Windows user name can be changed according to the user’s needs and requirement. The Windows 10 Windows Settings tool interface keeps changing after updates. It is a little hard to find out the tool to do the user name changing. One way to change Windows user name is to do it through the Computer
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How to Statically Link OCaml Programs
Posted onStatic linking is preferred for some cases although it has its own various problems. Static building/linking is not always possible for some languages on some platform. For OCaml, the answer to this question is yes. In this post, we will introduce 2 methods to statically linking OCaml: static linking with runtime glibc required and static
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How to write to remote side with sudo in rsync?
Posted onHere is the case, the user can not write directly to the remote side’s directory, while the user can sudo on the remote side and write the directory with sudo. How to write to remote side with sudo in rsync? On the source machine, run the rsync command with –rsync-path="sudo rsync" added. For example, rsync
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How to limit shared AWS EC2 accounts’ access to view and start all VMs yet stop only certain VMs
Posted onIf a team with many accounts share and manages the virtual machines under that same AWS accounts, it is a common practice to limit AWS EC2 accounts’ access to view or start all VMs yet stop only certain VMs. For example, one account has 50 VMs tagged “prod” while 25 VMs tagged “dev”. The developers
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How to do screen recording on Wayland in Linux?
Posted onHow to do screen recording on Wayland in Linux? Many screen recorders do not work on the new Wayland. Using Green Recorder You may try Green Recorder which supports Wayland. Note: Green Recorder is no longer under development by the original author (Please check the project README for more details). It still works well for
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How to enlarge root partition and filesystem size of cloud Linux VM at runtime without rebooting Linux
Posted onIt is common that the root disk space is not enough when running a Virtual Machine in the cloud such as Amazon Web Service (AWS). The cloud storage usually provides tools or facilities to enlarge a virtual disk size. However, to make the Linux recognize and and use the enlarged disks without rebooting the OS,
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Do big data stream processing in the stream way
Posted onReading: Years in Big Data. Months with Apache Flink. 5 Early Observations With Stream Processing: https://data-artisans.com/blog/early-observations-apache-flink. The article suggest adopting the right solution, Flink, for big data processing. Flink is interesting and built for stream processing. The broader view and take away may be to solve problems using the right solution. We saw many painful
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How to synchronize Google Drive and Google Docs files in Ubuntu/Debian/Mint Linux using Insync
Posted onGoogle Drive is a nice cloud storage service. It provides a suite of nice online document spreadsheet and slide editors Google Docs, Google Sheets and Google Slides. The collaborative editing and full history tracking features of Google Docs are excellent. Google Drive gives 16GB free storage which is pretty much larger compared to other free
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How to install GNOME 3 in Ubuntu MATE 18.04?
Posted onHow to install the GNOME 3 (gnome-shell) desktop environment in Ubuntu MATE 18.04? To install gnome3 to Ubuntu, install these packages sudo apt install gnome-session gdm3 ubuntu-desktop During installation, the installation tools will let you choose the default display manager. You may choose gdm3. Then reboot you Ubuntu Linux and gdm3 will be shown. Click
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Installing Zlib from Source Code in Ubuntu Linux
Posted onZlib is a popular open-source compression library used by many software applications to compress and decompress data. While it can be installed in Ubuntu using the apt package manager, you may need to install it from the source code if the version available in the Ubuntu repositories is outdated or if you need to customize
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Thunderbird Addons to Make Thunderbird Easier to Use
Posted onThunderbird is powerful and feature rich. But different users have different needs and it is not feasible to include all features into the base software, where a plugin system shines. Thunderbird, similar to Firefox from Mozilla, supports addons/plugins and has a large ecosystems. Here, we will introduce several addons to Thunderbird that make Thunderbird easier
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How to test a file or directory exists in Go?
Posted onHow to test a path (a file or directory exists) in golang? In Bash, the [ -e ] tests can test whether a file or a directory exist. What are the corresponding Go ways for the test? You can use the `os.Stat()` and `os.IsNotExist()` standard libraries functions together to test whether a file or a
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