Example Page
Bash
+--------------------+----------------------+-----------------+-----------------+
| Expression | parameter | parameter | parameter |
| in script: | Set and Not Null | Set But Null | Unset |
+--------------------+----------------------+-----------------+-----------------+
| ${parameter:-word} | substitute parameter | substitute word | substitute word |
| ${parameter-word} | substitute parameter | substitute null | substitute word |
| ${parameter:=word} | substitute parameter | assign word | assign word |
| ${parameter=word} | substitute parameter | substitute null | assign word |
| ${parameter:?word} | substitute parameter | error, exit | error, exit |
| ${parameter?word} | substitute parameter | substitute null | error, exit |
| ${parameter:+word} | substitute word | substitute null | substitute null |
| ${parameter+word} | substitute word | substitute word | substitute null |
+--------------------+----------------------+-----------------+-----------------+
Docker
Common commands:
docker-compose up
docker-compose up -d
docker-compose up -d my-api
docker-compose down
docker-compose logs
docker-compose logs -f --tail 100 my-api
Docker/AWS
Login to AWS ECR through a Docker container:
docker run --rm -it -v ~/.aws:/root/.aws amazon/aws-cli:latest ecr-public get-login-password --region us-east-1 | docker login --username AWS --password-stdin public.ecr.aws/<company>
Push an image to AWS ECR:
docker build -t image_ref .
docker tag <image_ref> public.ecr.aws/<ecr_name>/<repo_name>:latest
docker push public.ecr.aws/<ecr_name>/<repo_name>:latest
Docker/Azure
Run Azure CLI through Docker container:
docker run --rm -v "${HOME}/.azure:/root/.azure" mcr.microsoft.com/azure-cli
Python
python -m venv venv
pip install -r requirements.txt
# list comprehension
[(x, y) for x in [1,2,3] for y in [3,1,4] if x != y]
PowerShell
# Rename all files with creation date:
Get-ChildItem -Recurse *.txt | Rename-Item -newname {$_.CreationTime.toString("yyyyMMddHHmmss") + ".txt"}
Git
# Get lines of code by contributor
git ls-files | xargs -n1 git blame --line-porcelain | sed -n 's/^author //p' | sort -f | uniq -ic | sort -nr
# Change commit date
( GIT_COMMITTER_DATE="2023-11-15T13:46:00-07:00" GIT_COMMITTER_NAME="Some Author" GIT_COMMITTER_EMAIL="author.email@example.com" git commit --amend \ -m "Some message" \ --date "$GIT_COMMITTER_DATE" \ --author="$GIT_COMMITTER_NAME<$GIT_COMMITTER_EMAIL>" \ --allow-empty )
# Push branches from one remote to another
git push origin 'refs/remotes/origin-old/*:refs/heads/*'