Today I Learned

brew install ghostscript

#!/bin/bash
[ $# -lt 3 ] && { echo "Usage: $0 /input_dir /output_dir /quality"; exit 1; }
input_dir="$1"; output_dir="$2"; quality="$3"
mkdir -p "$output_dir"
for file in "$input_dir"/*.pdf; do
  base=$(basename "$file" .pdf)
  gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS="$quality" -dNOPAUSE -dQUIET -dBATCH -sOutputFile="$output_dir/${base}_compressed.pdf" "$file"
done

./compress_pdfs.sh /path/to/input /path/to/output /quality_setting

Quality options: /screen, /ebook, /printer, /prepress.

Say goodbye to online pdf converters.

Although it has improved lately for some services, AWS is still notoriously unfriendly when it comes to checking which services are activated and running across different regions. Here's a script you can run in the console to quickly see which regions have SES (Simple Email Service) available:

#!/bin/bash
for region in $(aws ec2 describe-regions --query "Regions[].RegionName" --output text); do
    echo "Checking SES in region: $region"
    if output=$(aws ses get-send-quota --region $region 2>&1); then
        echo "SES is active in region: $region"
        echo "$output"
    else
        echo "SES is not available in region: $region"
    fi
    echo "---------------------------------------"
done

This script loops through all AWS regions and checks if SES is running in each one, giving you a quick and easy overview of SES availability.

The output:

Checking SES in region: us-east-1
SES is active in region: us-east-1
{
    "Max24HourSend": 50000.0,
    "MaxSendRate": 14.0,
    "SentLast24Hours": 0.0
}
---------------------------------------
Checking SES in region: us-west-1
SES is not available in region: us-west-1
---------------------------------------
Checking SES in region: eu-west-1
SES is active in region: eu-west-1
{
    "Max24HourSend": 50000.0,
    "MaxSendRate": 10.0,
    "SentLast24Hours": 0.0
}
---------------------------------------

The problem

Deleting a huge folder structure is a pain and can take forever. However if you want to take forever divided by 3, you can use rsync.

It seems rsync is 3 time faster when deleting a huge folder structure than rm or find because it doesn't read the files before deleting.

The trick

• Create an empty folder in /tmp/empty_folder
• Run the command:

rsync -aP --delete ./empty_folder/ ./target_folder/

Enjoy!

In PHP, unlike JavaScript, we don't have native support for Promises or asynchronous programming. This limitation can become apparent when dealing with multiple HTTP requests that need to be made simultaneously. However, the Http::pool method, as shown in the code snippet, offers a workaround by allowing us to leverage parallel processing.

The code uses the HTTP pools functionality provided by the Laravel HTTP client, which is a convenient way to execute multiple HTTP requests concurrently. Here's an expanded explanation of the code:

//dummy code

$responses = Http::pool(fn (Pool $pool) => [
    $pool->get("https://jsonplaceholder.typicode.com/todos/1"),
    $pool->get("https://jsonplaceholder.typicode.com/users/1"),
    $pool->get("https://jsonplaceholder.typicode.com/posts/1")
]);

$todoInfo = $responses[0]->json();
$userInfo = $responses[1]->json();
$postInfo = $responses[2]->json();

This code snippet demonstrates how to make three (or more) simultaneous HTTP calls to different endpoints using HTTP pools in PHP. In a specific situation on the project I'm working on, this approach significantly reduced the load time from 3 seconds to 1.1 seconds.

Problem

Transfering files in the background via rsync is possible via nohup command and some other workarounds.

These don't really work when your transfer takes days (>50TB of data) because the background job might get killed by the system.

In order to create a persistent session we need to use tmux.

Solution

Authentication

Create a ssh key and upload it to the server you want to transfer from.

ssh-keygen -t ed25519
ssh-copy-id -i ~/.ssh/id_rsa.pub [your_old_server.domain.com]

Create a new session and run rsync

tmux new -s [your_session_name]

rsync --avhPW --stats [your_old_server.domain.com]:[/source/path/] [/destination/path]

Detach from session

Press CTRL+B and then D. You session will detach and run in background.

Re-attach session

To get back into your session just:

tmux a -t [your_session_name]

That's it.