DevOps
How to Use cloud init and User Data for Server Setup
Use cloud-init and user data to set up a server at first boot: users, SSH keys, packages, files and commands, plus how to debug a run that did nothing.
6 min read
Tag
users
7 posts
Shell Scripting
How to Validate User Input in a Shell Script the Safe Way
Validate input in a shell script by checking arguments, using allow lists, rejecting leading dashes, and quoting values before they reach commands.
6 min read
Regular Expressions
How to Use Named Capture Groups in Regex With Examples
Use named capture groups in regex: syntax in JavaScript, Python, PCRE and .NET, referring back by name, replacing with names and what grep, sed and awk lack.
6 min read
Docker
How to Run Docker Containers as a Non Root User the Safe Way
Run Docker containers as a non root user: the USER instruction, creating a user, file ownership, ports below 1024, and the runtime --user flag.
6 min read
Linux
How to Manage Groups on Linux With groupadd and usermod
Create groups with groupadd, add users with usermod -aG and gpasswd, list memberships with id, and learn why a new group needs a fresh login to take effect.
6 min read
Linux
How to Add Create and Delete Users on Linux
Add, modify and delete users on Linux with useradd, adduser and userdel, set the home directory and shell, and know which defaults a system account needs.
6 min read
Databases
How to Create Users and Grants From the Shell Safely
Create database users and grants from the shell for PostgreSQL and MySQL: least privilege, passwords kept off the command line, idempotent scripts and checks.
7 min read