sort and uniq Commands: Sort, Count and Deduplicate Lines
Sort text with sort (numeric, by column, human sizes, reverse), remove or count duplicates with uniq, and build top-N reports from server logs.
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Linux
Linux server administration: Debian, Ubuntu, AlmaLinux, storage, performance and troubleshooting.
Linux I/O Schedulers: none, mq-deadline, bfq, kyber Explained
Check and change the Linux I/O scheduler: none, mq-deadline, bfq and kyber explained, which suits SSDs, NVMe and VPS virtio disks, persistence, and measuring.
Linux Signals Explained: SIGTERM, SIGKILL, SIGHUP and More
Linux signals explained: SIGTERM, SIGKILL, SIGHUP and SIGINT, how services use them for reloads, graceful shutdown in apps and Docker, and trap in Bash.
.bashrc vs .bash_profile vs .profile: Which File Runs When?
Bash startup files explained: login vs interactive shells, when .bash_profile, .profile and .bashrc run, SSH and sudo behaviour, where PATH and aliases go.
tee Command in Linux: Write Output to a File and the Screen
Use tee to save command output while still seeing it, append with -a, write root-owned files with sudo tee, log scripts and split pipelines.
SNMP Monitoring on Linux: Install snmpd, v3 Users and Queries
Monitor Linux servers with SNMP: configure snmpd, secure SNMPv3 users, snmpwalk and snmpget, common OIDs, firewall rules, and Zabbix or LibreNMS.
Linux at Command: Schedule One-Time Jobs (atq, atrm, batch)
Run a command once later with at: enable atd, time formats, list and remove jobs with atq and atrm, batch for idle times, lockout safety nets, systemd-run.
tar Command in Linux: Create and Extract Archives
Create, list and extract tar archives with gzip, bzip2, xz and zstd compression, exclude files, extract single files and make reliable backups with tar.
Samba File Server on Linux: Share Folders With Windows and macOS
Set up a Samba file server on Linux: smb.conf shares, Samba users and permissions, SMB3 encryption, VPN-only access, and Windows, macOS and Linux clients.
Bash Functions: Arguments, Return Values and Local Variables
Write reusable Bash functions: syntax, arguments, return values and exit codes, local scope, error handling, libraries with source, and examples.
SSHFS: Mount a Remote Server Directory Over SSH
Mount remote folders over SSH with SSHFS on Linux, macOS and Windows: mount and unmount, reconnect options, permissions, fstab auto-mount, speed tips.
Check CPU Info on Linux: Cores, Model, Flags and Usage
Find CPU model, cores, threads, cache and flags on Linux with lscpu, nproc and /proc/cpuinfo, check AVX support, and see current CPU load.
Set Up an SFTP Server on Linux With Chroot Jails
Create a secure SFTP server with OpenSSH: SFTP-only users, chroot jails and permissions, SSH keys, logging, FileZilla and WinSCP, and common fixes.
Debian /etc/network/interfaces: Static IP, Extra IPs, ifupdown
Configure Debian networking with ifupdown: the /etc/network/interfaces format, static IPv4, DNS, extra IPs, applying changes safely, and cloud-init notes.
less Command in Linux: Page Through Files and Logs
Navigate large files with less: scrolling, searching, jumping to lines, following logs with F, filtering lines, opening compressed files and useful options.
Time Sync on Linux: Set Up chrony (NTP) on Ubuntu, Debian, RHEL
Keep server clocks accurate with chrony: install, choose NTP servers, check sync with chronyc, fix large offsets, and compare with systemd-timesyncd.
Configure Networking With nmcli (NetworkManager) on Linux Servers
Manage NetworkManager with nmcli: devices and connections, a static IP, DNS and gateway, extra IPs, applying changes safely, and nmtui on RHEL and AlmaLinux.
Bash Arrays: Indexed and Associative Arrays with Examples
Use Bash arrays: create, append, loop, slice and delete elements, associative arrays as maps, read command output into arrays, and pass arrays to commands.
Cron Environment Variables: PATH, SHELL, MAILTO and .env Files
Why commands fail under cron: the minimal cron environment, setting PATH, SHELL, MAILTO and CRON_TZ, loading .env files, nvm and virtualenvs, and debugging.
vmstat Command: Diagnose CPU, Memory, Swap and I/O on Linux
Read vmstat output column by column: run queue, blocked processes, swap in and out, I/O, context switches and CPU split, with real diagnosis examples.
Rename Multiple Files on Linux: mv Loops, rename and mmv
Batch rename files on Linux: Bash loops with parameter expansion, the Perl rename command, extensions and case, prefixes and dates, recursion, dry runs.
systemd Unit Files Explained: Write and Override Services
Write systemd service units: [Unit], [Service] and [Install], Type, Restart, User, Environment, overrides with systemctl edit, sandboxing, debugging.
Benchmark a VPS: CPU, Disk, Network and Web Server Tests
Benchmark a new VPS or dedicated server: sysbench and Geekbench for CPU, fio for disks, iperf3 and speedtest for network, and wrk or k6 for web.
Software RAID on Linux with mdadm (RAID 1, 5, 10 Setup)
Build and manage Linux software RAID with mdadm: choosing RAID levels, creating arrays, mdadm.conf, monitoring and alerts, replacing failed disks.