SysAdmin

File Operations Find and Replace Text sed -i 's/old-text/new-text/g' filename Replace all occurrences of ‘old-text’ with ’new-text’ in a file Quick File Search find . -name "*.txt" -type f -mtime -7 Find all .txt files modified in the last 7 days Move files with rsync and ssh rsync -avz -e "ssh -p 22" <source_file_or_dir> user@<remote_host>:/<remote_dir>/ Rsync via ssh. Port 22 is default but is added as a reminder that you might need to change to something else. ...

LocalSend is an open-source file transfer tool that operates on your local network. It’s the solution to the common problem: “I just want to send this file to my device over there.” It’s the best replacement for a “you wouldn’t have an empty usb stick somewhere, would you?” What Sets it Apart Works across all platforms (Windows, macOS, Linux, iOS, Android) No internet required No file size limits No accounts or setup No cloud storage costs Immediate transfers at network speed Real-World Use Cases Local Collaboration Share project files with teammates in the same office Transfer meeting recordings without uploading to cloud Exchange design assets between devices Media Management Move photos from phone to computer Transfer video files between editing devices Share music libraries locally Development Work Share builds with test devices Transfer datasets between machines Move VM images locally Home Network Share downloaded files between devices Back up phone photos to computer Move documents between family devices Why Choose LocalSend Over Cloud Storage Speed Transfers at local network speed (100MB/s+) No upload/download waiting time No internet bandwidth used Privacy Files never leave your network No third-party servers involved Complete control over your data Simplicity Select files → pick device → send No syncing issues No storage management No subscription Getting Started Download from your platform’s store or GitHub Install on your devices Ensure devices are on same WiFi Start sending files Technical Notes Uses HTTP protocol for transfers TLS encryption for security mDNS for device discovery Works on both IPv4 and IPv6 networks Common Questions Q: Is it really free? A: Yes, completely free and open source. ...

If you’re running automated backups on a laptop, traditional schedulers like cron or fcron might not be ideal. Your machine isn’t always on, and you might want to trigger backups specifically when the system starts up or wakes from sleep. Here’s how to use systemd to run your backup script at these key moments. The systemd Service File Create /etc/systemd/system/backup.service: [Unit] Description=Run backup script at boot and wake-up After=multi-user.target suspend.target hibernate.target hybrid-sleep.target suspend-then-hibernate.target [Service] Type=oneshot User=yourusername Group=yourgroup ExecStart=/path/to/backup-script.sh [Install] WantedBy=multi-user.target suspend.target hibernate.target hybrid-sleep.target suspend-then-hibernate.target The User and Group directives ensure the script runs as your user instead of root. This is important for: ...

Getting Started with Ansible for Linux System Administration System administration can be tedious and time-consuming, especially when managing multiple remote servers. Ansible provides a powerful solution for automating these tasks, making server management more efficient and less error-prone. Here’s how to set up Ansible and create your first playbooks for managing Linux servers. Key Concepts Ansible: An automation tool that uses YAML for defining configurations, making it human-readable and easy to manage. It operates over SSH, requiring no agents on remote systems. ...

Mosh (Mobile Shell) is a userland remote terminal application that provides resilient connections surviving network changes and interruptions. Unlike traditional system daemons, Mosh runs entirely in userspace, providing natural security boundaries and simplified deployment. How Mosh Works Userland Architecture Mosh operates entirely in userspace, which is fundamentally different from traditional SSH: Initial Connection Uses existing SSH for authentication SSH launches mosh-server as your user (not root) Server picks available UDP port Communicates port and key back through SSH Local mosh-client establishes UDP connection Security Benefits ...