DEV Community: Nam Hoang

Handy Sed One-Liners for Text Manipulation and Processing

Nam Hoang — Mon, 01 Apr 2024 02:34:35 +0000

FILE SPACING:

Double space a file:

sed G

Double space a file which already has blank lines, output file should contain no more than one blank line between lines of text:

sed '/^$/d;G'

Triple space a file:

sed 'G;G'

Undo double-spacing (assumes even-numbered lines are always blank):

sed 'n;d'

Insert a blank line above every line which matches "regex":

sed '/regex/{x;p;x;}'

Insert a blank line below every line which matches "regex":

sed '/regex/G'

Insert a blank line above and below every line which matches "regex":

sed '/regex/{x;p;x;G;}'

NUMBERING:

Number each line of a file (simple left alignment):

sed = filename | sed 'N;s/\n/\t/'

Number each line of a file (number on left, right-aligned):

sed = filename | sed 'N; s/^/     /; s/ *\(.\{6,\}\)\n/\1  /'

Number each line of file, but only print numbers if line is not blank:

sed '/./=' filename | sed '/./N; s/\n/ /'

Count lines (emulates "wc -l"):

sed -n '$='

TEXT CONVERSION AND SUBSTITUTION:

Convert DOS newlines (CR/LF) to Unix format:

sed 's/.$//'

Convert Unix newlines (LF) to DOS format:

sed "s/$/`echo -e \\\r`/"

Delete leading whitespace (spaces, tabs) from front of each line:

sed 's/^[ \t]*//'

Delete trailing whitespace (spaces, tabs) from end of each line:

sed 's/[ \t]*$//'

Delete both leading and trailing whitespace from each line:

sed 's/^[ \t]*//;s/[ \t]*$//'

Insert 5 blank spaces at beginning of each line (make page offset):

sed 's/^/     /'

Align all text flush right on a 79-column width:

sed -e :a -e 's/^.\{1,78\}$/ &/;ta'

Center all text in the middle of 79-column width:

sed  -e :a -e 's/^.\{1,77\}$/ & /;ta'

Substitute (find and replace) "foo" with "bar" on each line:

sed 's/foo/bar/'

Substitute "foo" with "bar" EXCEPT for lines which contain "baz":

sed '/baz/!s/foo/bar/g'

Reverse order of lines (emulates "tac"):

sed '$!G;h;$!d'

Join pairs of lines side-by-side (like "paste"):

sed '$!N;s/\n/ /'

If a line ends with a backslash, append the next line to it:

sed -e :a -e '/\\$/N; s/\\\n//; ta'

Add a blank line every 5 lines:

gsed '0~5G'

SELECTIVE PRINTING OF CERTAIN LINES:

Print first 10 lines of file (emulates behavior of "head"):

sed 10q

Print first line of file (emulates "head -1"):

sed q

Print the last 10 lines of a file (emulates "tail"):

sed -e :a -e '$q;N;11,$D;ba'

Print only lines which match regular expression (emulates "grep"):

sed -n '/regexp/p'

Print only lines which do NOT match regexp (emulates "grep -v"):

sed '/regexp/!d'

Print paragraph if it contains AAA:

sed -e '/./{H;$!d;}' -e 'x;/AAA/!d;'

Print section of file from regular expression to end of file:

sed -n '/regexp/,$p'

SELECTIVE DELETION OF CERTAIN LINES:

Print all of file EXCEPT section between 2 regular expressions:

sed '/Iowa/,/Montana/d'

Delete duplicate, consecutive lines from a file (emulates "uniq"):

sed '$!N; /^\(.*\)\n\1$/!P; D'

Delete all blank lines from a file:

sed '/^$/d'

Delete all consecutive blank lines from file except the first:

sed '/./,/^$/!d'

Delete all trailing blank lines at end of file:

sed -e :a -e '/^\n*$/{$d;N;ba' -e '}'

SPECIAL APPLICATIONS:

Remove nroff overstrikes (char, backspace) from man pages:

sed "s/.`echo \\\b`//g"

Get Usenet/e-mail message header:

sed '/^$/q'

Get Usenet/e-mail message body:

sed '1,/^$/d'

Add a leading angle bracket and space to each line (quote a message):

sed 's/^/> /'

Delete leading angle bracket & space from each line (unquote a message):

sed 's/^> //'

Remove most HTML tags:

sed -e :a -e 's/<[^>]*>//g;/</N;//ba'

Extract multi-part uuencoded binaries:

sed '/^end/,/^begin/d' file1 file2 ... fileX | uudecode

SORTING PARAGRAPHS OF FILE ALPHABETICALLY:

sed '/./{H;d;};x;s/\n/={NL}=/g' file | sort | sed '1s/={NL}=//;s/={NL}=/\n/g'

OPTIMIZING FOR SPEED:
Substitution executes more quickly if the "find" expression is specified before the "s/.../.../" instruction:

sed '/foo/ s/foo/bar/g' filename

A task vs a script in Hardhat

Nam Hoang — Mon, 25 Mar 2024 08:19:38 +0000

Understanding the Distinctions Between Tasks and Scripts in Hardhat

It's crucial to grasp that nearly everything achievable with a task can also be accomplished with a script, and vice versa. However, there are nuances: certain actions are exclusive to tasks or scripts, and some tasks are more suited to one or the other.

Tasks:

One fundamental capability exclusive to tasks is the ability to override another task. For instance, consider augmenting your test workflow:

task("test", async (args, hre, runSuper) => {
  // Perform additional actions
  return runSuper();
})

What about custom tasks? In this scenario, tasks and scripts are essentially interchangeable. The primary advantage of utilizing a task lies in integrating with Hardhat's argument parser. For instance, when developing a token and needing to verify an address's balance on a specific network, you might execute:

hh balance --address 00x4403B5d2Fed270D18b6d83122C818c2413D9BC05 --network mainnet

(Where 'hh' represents the Hardhat shorthand.)

Scripts:

One distinctive feature of scripts is their executability directly via Node.js. Instead of:

hh run my-script.js

You have the option to use:

node my-script.js

This flexibility enables additional functionalities such as passing extra flags to the Node.js binary. Furthermore, it facilitates execution with alternative binaries like ts-node, ndb, or mocha.

It's worth noting that when adopting this approach, explicit importation of the Hardhat Runtime Environment is necessary:

const hre = require("hardhat");

Alternatively, utilize:

node --require hardhat/register my-scripts.js

to ensure the availability of globally scoped variables, akin to those accessible when using 'hh run'.

Another rationale for employing scripts is the ability to leverage alternative argument-parsing libraries like commander, rather than relying on Hardhat's built-in parser.

However, bear in mind that this approach forfeits the ability to specify the network using the '--network' parameter. In such cases, setting the 'HARDHAT_NETWORK' environment variable becomes necessary:

HARDHAT_NETWORK=rinkeby node my-scripts.js

Understanding these distinctions empowers developers to choose the appropriate tool—task or script—based on the specific requirements of their development workflow.

References:

https://ethereum.stackexchange.com/questions/83656/where-does-the-line-blur-between-a-task-and-a-script-in-hardhat

Blockchain Network List

Nam Hoang — Fri, 01 Mar 2024 11:05:06 +0000

OP Testnet (Sepolia)

Network name: OP Sepolia
New RPC URL: https://sepolia.optimism.io
Chain ID: 11155420
Currency symbol: ETH
Block explorer URL (Optional): https://sepolia-optimistic.etherscan.io
Faucet:
- https://learnweb3.io/faucets/optimism_sepolia/

Useful Links:

https://docs.optimism.io/chain/networks

Base Testnet (Sepolia)

Network name: Base Sepolia
New RPC URL: https://sepolia.base.org
Chain ID: 84532
Currency symbol: ETH
Block explorer URL (Optional): https://sepolia-explorer.base.org
Faucet:

Useful Links:

https://docs.base.org/docs/network-information/

Arbitrum Sepolia

Network name: Arbitrum Sepolia
New RPC URL: https://sepolia-rollup.arbitrum.io/rpc
Chain ID: 421614
Currency symbol: ETH
Block explorer URL (Optional): https://sepolia.arbiscan.io

Useful Links:

Polygon Amoy

Network name: Polygon Amoy Testnet
New RPC URL: https://rpc-amoy.polygon.technology/
Chain ID: 80002
Currency symbol: MATIC
Block explorer URL (Optional): https://www.oklink.com/amoy
Faucet:
- https://www.alchemy.com/faucets/polygon-amoy
- https://faucet.polygon.technology/

BNB Chain Testnet

Network name: BNB Chain Testnet
New RPC URL: https://data-seed-prebsc-1-s1.bnbchain.org:8545
Chain ID: 97
Currency symbol: tBNB
Block explorer URL (Optional): https://testnet.bscscan.com

Useful Links:

This list serves as a personal note of frequently used blockchain networks, shared for anyone in need. While it may not be exhaustive, it aims to provide convenient access to essential information. Your understanding is appreciated! 😄

NVM tips and tricks

Nam Hoang — Tue, 06 Feb 2024 09:40:10 +0000

1. How to uninstall nvm?

just remove directory

rm -rf $NVM_DIR ~/.npm ~/.bower

https://github.com/nvm-sh/nvm/issues/298#issuecomment-30654686

2. Install NVM with .nvm being installed in a different directory

Simply set $NVM_DIR before running the install script

export NVM_DIR=$(pwd)/workspace/.nvm && curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.39.7/install.sh | bash

https://github.com/nvm-sh/nvm/issues/1436

How to connect to Mongo database using Mongo shell on Ubuntu?

Nam Hoang — Mon, 29 Jan 2024 20:56:33 +0000

Introduction

MongoDB, a widely used NoSQL database, provides developers with a flexible and scalable solution for managing large datasets. Connecting to a MongoDB database using the Mongo Shell is an essential skill for both developers and administrators. In this article, we will guide you through the step-by-step process of connecting to a MongoDB database using the Mongo Shell.

Prerequisites

To utilize the MongoDB Shell, you need a MongoDB deployment to connect to.

For a free cloud-hosted deployment, consider using MongoDB Atlas.
If you want to run a local MongoDB deployment, refer to the Install MongoDB documentation.

Supported MongoDB Versions:
You can use the MongoDB Shell to connect to MongoDB version 4.2 or greater.

Step 1: The following instructions are for Ubuntu 22.04 (Jammy).

Install gnupg and its required libraries:
```
sudo apt-get install gnupg
```

Retry importing the key:

wget -qO- https://www.mongodb.org/static/pgp/server-7.0.asc | sudo tee /etc/apt/trusted.gpg.d/server-7.0.asc

Create the /etc/apt/sources.list.d/mongodb-org-7.0.list file for Ubuntu 22.04 (Jammy):

echo "deb [ arch=amd64,arm64 ] https://repo.mongodb.org/apt/ubuntu jammy/mongodb-org/7.0 multiverse" | sudo tee /etc/apt/sources.list.d/mongodb-org-7.0.list

Reload the local package database:
```
sudo apt-get update
```

Install the mongosh package:

sudo apt-get install -y mongodb-mongosh

Confirm that mongosh installed successfully:
```
mongosh --version
```

Step 2: Connect to MongoDB Atlas with mongosh

To establish your connection, run the mongosh command with your connection string and options:

The connection string includes the following elements:

Your cluster name
A hash
A flag for the API version
A flag for the username you want to use to connect

It resembles the following string:

mongosh "mongodb+srv://YOUR_CLUSTER_NAME.YOUR_HASH.mongodb.net/" --apiVersion YOUR_API_VERSION --username YOUR_USERNAME

# for example
mongosh "mongodb+srv://db.fakeuri.mongodb.net/" --apiVersion 1 --username admin

Step 3: Run Commands

Switch Databases

To display the current database, use the following command:

db

This operation should return test, which is the default database. To switch databases, use the use <db> helper, as shown in the example below:

use <database>

Create a New Database and Collection

To create a new database, use the use <db> command with the desired database name. For instance, the following commands create the myNewDatabase database and the myCollection collection using the insertOne() operation:

use myNewDatabase
db.myCollection.insertOne( { x: 1 } );

If the collection does not exist, MongoDB creates it when you first store data for that collection.

Terminate a Running Command

To terminate a running command or query in mongosh, press Ctrl + C. When you enter Ctrl + C, mongosh:

Interrupts the active command.
Tries to terminate the ongoing, server-side operation.
Returns a command prompt.

If mongosh cannot cleanly terminate the running process, it issues a warning.

Conclusion

Connecting to a MongoDB database using the Mongo Shell is a straightforward process that involves a few simple steps. Whether you're a developer building applications or an administrator managing databases, mastering the basics of the Mongo Shell is crucial for efficient MongoDB usage. Now that you've learned the essentials, you can explore further commands and functionalities to harness the full power of MongoDB for your projects.

The lessons I learned after having a micro launch of my product on Reddit

Nam Hoang — Fri, 26 Jan 2024 11:22:44 +0000

First, I'd like to introduce my product a bit. My product is a 2048 game website. I chose 2048 game as the game because I was quite addicted to it when it was first released in 2014. In my opinion, it's a simple game but challenging to master. I also have quite a few ideas for it. Seeing successful websites like online-solitaire.com only strengthens my belief in my principle: Doing something as simple but achieving it to perfection will lead you to success!

I create a website using my familiar technical stack: Next.js and Netlify. I spent about 20 hours building the initial version that could run, but I was not satisfied with the performance and the codebase. I thought it was very difficult to be extended. I then spent another 20 hours to rewrite the codebase and fix some performance issues.

Finally, there was no plan beforehand. I just wanted to post it on a few subreddits and see people's reactions. Surprisingly, the majority of the responses were positive, and some were just about bugs and suggestions for new features. Here are the things I learned:

Focus on one feature and do it well. Let the users feel comfortable using it. I have quite a few features I want to add, like a leaderboard and some other game variations. But that's for the future.
Don't be afraid to do things no one else wants to do. When I started, I thought no one would want another 2048 game website. But here we are.

That's all for today's sharing! Please follow the page! I will update the project's progress here ^^

Origin: https://www.namvhoang.com/blogs/2023-11-21-lessons-learned-micro-launch-product-reddit/