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This notes is written by Sheldon. You can find me with #iOSBySheldon in Github, Youtube, Facebook, etc.

Need

Convert .mov/.MP4 to .gif

Reason

As a developer, I feel better to upload a short video when I create the pull request to show other viewers what I did in this PR. I tried .mov format directly got after finishing recording screen using Quicktime, however, gif offers preview in most web pages, and has smaller file size.

This is not limited to developer, anyone has this need can use this method to convert the files.

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# Define where to store the generated certs and metadata.
DIR="$(pwd)/tls"

# Optional: Ensure the target directory exists and is empty.
rm -rf "${DIR}"
mkdir -p "${DIR}"

# Create the openssl configuration file. This is used for both generating
# the certificate as well as for specifying the extensions. It aims in favor
# of automation, so the DN is encoding and not prompted.

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set -e, -u, -o, -x pipefail

The set lines

• These lines deliberately cause your script to fail. Wait, what? Believe me, this is a good thing.
• With these settings, certain common errors will cause the script to immediately fail, explicitly and loudly. Otherwise, you can get hidden bugs that are discovered only when they blow up in production.

• set -euxo pipefail is short for:

set -e
set -u

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Shell file test operators

Usage

FILE=/etc/passwd

if test -f "$FILE"; then
    echo "$FILE exist"
fi

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Docker containers logs clearing script

chmod +x ./clear_docker_container_logs.sh

Usage

Usage: ../clear_docker_container_logs.sh [-c ""]

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Removing intermediate images left over from multiple builds

docker rmi $(docker images -a --filter=dangling=true -q)

Removing stopped containers

docker rm $(docker ps --filter=status=exited --filter=status=created -q)

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Reset origin to commit

git log
git reset --hard <commit-hash>
git push --force origin master

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