Linux & System Administration

Terminal screenshot showing iostat output with per-device read/write throughput, IOPS, KB/s, avg wait and service time, device utilization %, and CPU stats for disk I/O monitoring.

Illustration showing generating an SSH key pair, copying the public key to a remote server, enabling key-based authentication, and connecting securely via SSH without a password.!!

Terminal window showing .bashrc with alias examples: ll='ls -alF', gs='git status', safer rm alias, PATH export, and a command to source the file to apply new aliases immediately.!

Illustration comparing SysV runlevels (0-6) with systemd targets, showing mappings to rescue, multi-user, graphical, shutdown and reboot, plus service units and boot sequence flow.

Terminal mockup showing journalctl usage: examples of filtering by unit and priority, selecting time ranges, following logs paging output, and exporting JSON (-o json) for analysis.

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Diagram of Linux 'Permission denied' troubleshooting: terminal errors, file permissions, sudo, chmod/chown, owner/group checks, execute bits, path issues, and corrective commands .

Illustration of setting Linux file descriptor limits using ulimit: terminal window showing commands, config files, soft vs hard limits, systemd and /etc/security/limits.conf tips..

Linux DNS server v4 configuration workflow showing editing /etc/resolv.conf, named.conf, zone files, systemd-resolved settings, testing with dig, nslookup, and restarting services.

Sysadmin reviews disk partitions in a GUI: partition map, used/free bars, mount points, actions to resize, format, create or delete partitions, with warning prompts visible +logs.!