Command Crate

ffmpeg -nostats -i pohokolius_-_odlazak_remastered.flac -af astats=metadata=0 -f null - 2>&1 | grep "Bit depth"

This commands exposes effective depth of an audio file. Example: if it comes back as something like 16/24/24/24, the source was 16-bit content in a 24-bit wrapper.

grep -E '^he_' /var/run/hostapd-phy*.conf | grep -v mu_edca

Dumps the active 802.11ax operating parameters minus the MU-EDCA defaults. Shows he_oper_chwidth (0=20/40, 1=80, 2=160), spatial reuse control, BSS color, TWT requirement and beamforming roles in one view.

iw phy1 info | grep -A 10 'valid interface combinations'

Reports the maximum number of AP interfaces the radio hardware supports.

iw dev phy1-ap0 station dump | grep -c Station

Counts currently associated wireless clients on an interface. Useful for checking whether a txpower reduction dropped edge clients, when run repeatedly over time.

iw dev phy1-ap0 station dump | grep -E 'Station|signal:|tx bitrate|rx bitrate'

Shows per-client uplink signal and negotiated rates. Only measures what the AP receives, so it cannot be used to evaluate AP transmit power changes. Clients must be passing traffic or rates read low.

iw dev phy1-ap0 survey dump | grep -A7 'in use'

Reports noise floor plus channel active/busy time for the operating channel. Divide busy by active for airtime utilization; under ~20 percent is healthy, over ~50 percent means real contention.

iwinfo phy1-ap0 info | grep -E 'Channel|Tx-Power'

Shows the channel, center channel, HT mode and post-regdb-clamp Tx-Power actually in effect on a wireless interface.

magick pokloni-website-card_1200x600.png -resize "1200x630^" -gravity center -extent 1200x630 pokloni-website-card_1200x600_fixed.png

Resizes an image to fill a 1200x630 canvas, centering the content and cropping any overflow.

python3 -c "import re,sys,pathlib;p=re.compile(r'[\U0001f300-\U0001f9ff\U00002702-\U000027b0\U0000fe00-\U0000fe0f\U0000200b-\U0000200f\U0000200d]');[print(f'{f}:{i+1}: {l.rstrip()[:80]}') for f in pathlib.Path(sys.argv[1]).rglob('*') if f.suffix in ('.html','.md','.txt') for i,l in enumerate(f.read_text('utf-8').splitlines()) if p.search(l)]" ./

Scans all .html, .md, and .txt files recursively for emoji and zero-width characters (ZWJ, variation selectors, invisible formatters). Prints filename:line:preview for each hit. Safe for multilingual content (Cyrillic, CJK etc.), only targets Unicode emoji and control ranges.

pkg info -r ImageMagick7

Lists all installed packages that depend on a given package.

gzip --best -k file.svg && mv file.svg.gz file.svgz

Compresses an SVG file into the SVGZ format. The -k flag preserves the original.

dnf repoquery --installed --whatrequires ImageMagick7

Lists all installed packages that depend on a given package. Answers: 'what would break if I removed this?'

magick main_screen.png -background none -size 20x1 xc:none results.png +append kalkulator-prostih-brojeva-app-pregled.png

Horizontally appends images with a transparent spacer between them. Creates a 20x1 transparent canvas as a gap, then uses +append to stitch all images side by side into a single output file.

awk -F'[<>]' '/<loc>/ {print $3}' sitemap.xml

Extracts raw URLs from a standard XML sitemap with awk. Matches and captures text strictly between <loc> tags.

sed -n 's/.*<loc>\(.*\)<\/loc>.*/\1/p' sitemap.xml

Extracts raw URLs from a standard XML sitemap. Matches and captures text strictly between <loc> tags, replacing the entire line with the URL. Works on FreeBSD/BSD sed.

top -o res

Sorts FreeBSD process list by resident set size (RSS, physical RAM). Essential for ignoring misleading virtual memory ('SIZE') stats, which often show terabytes of reserved address space for electron/Go apps. 'RES' reveals the actual physical memory cost.

magick gshock-gw-m5610u-1b.png -fill "#fbfbfe" -opaque "#e6f1f5" -fill "#1c1b22" -opaque "#203a43" gshock-gw-m5610u-1b_darkgrey.png

Swaps specific hex colors 1:1 on the image. Replaces Light (#e6f1f5) with off-white (#fbfbfe) and dark (#203a43) with dark-grey (#1c1b22). Uses sequential fill/opaque operations.

printf 'dev.hwpstate_intel.0.epp=100\ndev.hwpstate_intel.1.epp=100\ndev.hwpstate_intel.2.epp=100\ndev.hwpstate_intel.3.epp=100\n' | sudo tee -a /etc/sysctl.conf && sudo sysrc powerd_enable='NO'

Appends Intel HWP powersave settings to sysctl.conf (making them permanent) and disables the obsolete 'powerd' service in rc.conf. Useful for libreboot systems.

sysctl dev.cpu.0.freq_levels

Checks available CPU frequency steps. If output is single-level (e.g., '2700/-1') on Libreboot/modern Intel, ACPI tables are missing. Discard 'powerd' and rely on 'hwpstate_intel' (Hardware P-States) for frequency scaling.

sysctl dev.hwpstate_intel.0.epp=100

Sets Intel Speed Shift (HWP) to 'Powersave' (Energy Performance Preference = 100) on CPU core 0 (first). Use '50' for Balanced or '0' for Performance. Required on modern Intels where 'powerd' has no effect.

sysctl dev.cpu.0.freq dev.cpu.0.freq_levels dev.cpu.0.cx_supported dev.cpu.0.cx_lowest

Displays current CPU frequency, available scaling levels, and supported C-states (sleep modes). Essential for verifying if FreeBSD is correctly entering low-power idle states.

magick input.xcf -flatten -resize 3000x3000 -strip -quality 92 output.jpg

Directly converts a GIMP XCF project file to JPEG without opening GIMP. '-flatten' merges all layers onto a white background (crucial for XCF), '-resize' sets the dimensions, and '-strip' removes all metadata/EXIF for a clean, smaller file.

magick rss-icon.png -quality 75 -define webp:method=6 -define webp:pass=10 rss-icon.webp

Converts PNG to WebP with 'Max Effort' settings. Method 6 enables the most computationally expensive compression algorithms, and pass 10 iteratively optimizes the quantization. Uses standard YUV 4:2:0 chroma subsampling for minimum file size.

magick -background none -density 648 favicon.svg rss-icon.png

Crisp SVG to PNG conversion. The density must be calculated: (TargetWidth / SourceWidth) * 72. Example: 144 / 16 = 9. 9 * 72 = 648. This forces 1:1 rendering without blurring.

ffmpeg -i pohokolius_-_tetrahedron.flac -filter_complex "[0:a]avectorscope=s=640x640:rate=25:zoom=1.5:draw=line" -y tetrahedron_phase.mp4

Generates a visual phase analysis video (Goniometer/Lissajous) from the audio stream. Vertical alignment indicates mono compatibility; horizontal alignment indicates phase cancellation. The 'cloud' shape represents stereo width. Ideal for checking mastering results!

ffmpeg -i pohokolius_-_tetrahedron.flac -filter_complex "pan=mono|c0=c0-c1" -y tetrahedron_side_signal.wav

Isolates the side signal (stereo difference). Subtracts right audio channel from Left. Used to audit exactly what 'space' and 'air' will be deleted when the track is played on mono systems. Ideal for checking mastering results!

adb push ./local_file /sdcard/Download/

The only way to write to Android at full speed (20-40MB/s). Helps with MTP/FUSE bottleneck.

ffmpeg -i input.wav -af "pan=stereo|c0=c0|c1=-1*c1" phase_flip.wav

Inverts the phase of the right audio channel. If the cancellation was caused by a simple polarity inversion, this restores the sound while keeping some stereo information.

ffmpeg -i input.wav -af "pan=stereo|c0=c0|c1=c0" vangogh.wav

Discards the right audio channel entirely and forces the left channel to both speakers. Fixes some phase cancellation issues by killing stereo.

ffmpeg -i input.wav -codec:a libmp3lame -q:a 0 output.mp3

Converts audio to MP3 using variable bitrate (VBR) set to V0 (highest VBR quality, efficient size).

ffmpeg -i input.wav -codec:a libmp3lame -b:a 320k output.mp3

Converts audio to MP3 using constant bitrate (CBR) at 320kbps (highest standard quality).

magick input.png -resize 1000x1000 -quality 90 output.jpeg

Resizes an image to fit within 1000x1000px (maintaining aspect ratio) and saves as 90% quality JPEG.

magick input.png -define jpeg:extent=1.8MB output.jpeg

Converts an image to JPEG, automatically adjusting quality to ensure the file size is under the specified limit (e.g., 1.8MB).

magick cover.png \( -background none -size 200x200 logo.svg \) -gravity SouthEast -geometry +100+100 -composite output.png

Overlays a vector logo onto a base image. Resizes the logo cleanly to 200px and places it 100px from the bottom-right corner.

metaflac --remove --block-type=PICTURE file.flac && metaflac --import-picture-from="cover.jpg" file.flac

Safely removes old artwork first, then embeds the new cover image in a second pass in a music file.

ffmpeg -i input.flac -af loudnorm=I=-12:TP=-2:LRA=7:print_format=summary -c:a flac -sample_fmt s32 -ar 48000 output.flac

The 'Streaming Safe' Master. Normalizes audio to -12 LUFS and -2.0 True Peak. Preserves 24-bit depth and 48kHz rate.

etcupdate diff | less

Compares your current /etc configuration files against the stock defaults. Shows exactly what you have modified.

bastille cmd ALL ping -c 1 8.8.8.8

The 'Smoke Test': Verifies that your PF Firewall NAT is actually working by forcing all Jails to ping Google.

service pf reload

Reloads the PF firewall rules immediately (applies changes).

pfctl -nf /etc/pf.conf

Checks the PF configuration file for syntax errors WITHOUT loading it (Safe Mode).

fsck -t ufs -f -y /dev/da0p1

Forces a full consistency check and auto-repair on a UFS partition, even if marked 'clean'. Equivalent to 'e2fsck -f'.

tunefs -n enable /dev/da0p1

Enables 'Soft Updates'. Reorders disk writes to ensure filesystem structure remains consistent even if power fails.

tunefs -t enable /dev/da0p1

Enables TRIM support on a UFS partition. CRITICAL for SSD longevity and sustained write speeds.

tunefs -j enable /dev/da0p1

Enables 'Soft Updates Journaling' (SU+J). Makes filesystem recovery near-instant after a power failure.

tunefs -p /dev/da0p1

Prints all current UFS tuning parameters (ACLs, Journal, Soft Updates, Trim, Owner).

tunefs -m 0 /dev/da0p1

Reduces the reserved space (minfree) on a UFS partition to 0%, instantly reclaiming ~8% of disk capacity (useful for data/backup drives).

fsck -t ufs -y /dev/da0p1

Runs a non-interactive (-y) consistency check and repair on a UFS partition.

e2fsck -f /dev/da0p1

Forces a filesystem consistency check and repair on Ext2, Ext3, or Ext4 partitions (fixes 'dirty' bit).

tune2fs -L "NEW_LABEL" /dev/da0p1

Renames (relabels) an Ext2, Ext3, or Ext4 filesystem without reformatting.

sysupgrade -b /tmp/backup.tar.gz

Creates a backup archive of the current configuration and saves it to /tmp.

block info

Displays UUIDs, labels, filesystem types, and mount points for all attached block devices. Requires block-mount package.

whereis -b ansible

Locates the binary executable for a specific program.

/usr/libexec/locate.updatedb

Manually updates the 'locate' database to index recent files.

procstat -f $(pgrep nginx)

Lists all open files and file descriptors for a specific process (like lsof).

pfctl -s info

Shows the current status of the PF firewall (uptime, stats, state table).

service -e

Lists all system services that are currently enabled.

sockstat -4l

Lists all IPv4 listening sockets and the processes/PIDs attached to them.

kldstat -v

Lists all loaded kernel modules and the specific kernel files they belong to.

pciconf -lv

Lists all PCI devices attached to the system showing driver names and vendor details.

service powerd status

Checks if the power control daemon is running.

sysctl dev.cpu.0.cx_usage

Displays usage statistics for CPU C-states (sleep modes).

sysctl dev.cpu.0.freq_levels

Lists all supported frequency steps and their power consumption.

sysctl dev.cpu.0.freq

Displays the current operating frequency (MHz) of the first CPU core.

sysctl dev.cpu | grep temperature

Displays the current temperature of all CPU cores.

top -P -d 1

Runs top in per-CPU mode (-P) with a 1-second refresh rate.

bastille rdr target_jail tcp 8080 80

Forwards TCP port 8080 on the host to port 80 inside the target jail (requires PF).

bastille stop target_jail

Gracefully stops a specific jail.

bastille cmd ALL echo 'Hello World'

Executes a single command across ALL running jails simultaneously.

bastille console hlab-ansible-server

Logs directly into the shell of a specific running jail.

bastille list

Displays a table of all Bastille jails, including their state (up/down) and IP addresses.

pkg audit -F

Fetches the latest vulnerability database and audits all installed packages for known security issues.

pkg info -as | sort -hk 2

Lists all installed packages sorted by their installed size (human-readable).

pkg query -e '%a = 0' '%n-%v'

Lists 'leaf' packages (software you explicitly installed), excluding dependencies.

bectl create -r pre-update-backup

Creates a new ZFS Boot Environment recursively, allowing you to rollback the entire OS if an update fails.

bectl list

Lists all ZFS Boot Environments (BEs), showing which is active now and which will be active on the next reboot.

zpool scrub zroot

Initiates a data integrity check (scrub) on the main ZFS pool to verify checksums and repair corruption.

zpool status -v zroot

Checks the progress of a running ZFS scrub or displays detailed error logs for the pool.

zpool list -v

Shows the status and topology of ZFS pools, including individual read/write/checksum errors for specific drives.

zfs list -o space

Displays a detailed breakdown of ZFS disk usage, distinguishing between data, snapshots, and reserved space.

glabel status

Shows all available labels (UFS, GPT, Ext2fs) and which physical device they point to.

geom disk list

Lists detailed physical attributes of all connected disks (mediasize, sector size, rotation rate, device names).

tune2fs -L "DATA_VAULT" /dev/da0s1

Labels an existing Ext4 partition.

tune2fs -O ^has_journal /dev/da0s1

Disables the journal on an existing Ext4 partition to allow high-speed mounting on FreeBSD.

mount -o async,noatime /dev/ufs/DATA-DISK /media/DATA-DISK

Mounts a UFS drive in 'Turbo Mode' (Write Caching + No Access Time). Fast for backups (130MB/s+).

tunefs -L "DATA-DISK" /dev/da0p1

Writes a label to an EXISTING UFS partition. Makes it appear permanently as /dev/ufs/DATA-DISK.

rsync -avhW --no-compress --info=progress2 /source/ /media/DATA-DISK/

('Turbo' Rsync) Uses whole-file copy (-W) and disables compression to maximize throughput on local USB drives.

dd if=/dev/zero of=/media/DATA-DISK/speedtest.img bs=1M count=1000 status=progress

Writes a 1GB sequential test file to check the pure write speed of a drive, bypassing filesystem overhead.

cmp ./Samsung_SSD_990_PRO_8B2QJXD7.iso /dev/sdb

Compares the contents of an ISO file against a physical disk to ensure the data was written accurately byte-for-byte.

: > /path/to/big.log

The fastest way to truncate a file to zero bytes. The colon ':' is the null command (does nothing), and the redirection operator opens the file and truncates it. Atomic and faster than 'echo'.

echo "${SRANDOM}"

Bash 5.1+ Only. Returns a cryptographically secure 32-bit random number from the kernel's entropy pool, unlike $RANDOM which is linear and predictable. No need to cat /dev/urandom anymore.

assoc .txt=txtfile

Fix file associations via command line. Links .txt extension back to text files.

dism /online /export-driver /destination:C:\BackupDrivers

Export all installed 3rd-party drivers to a folder. Essential before reinstalling Windows.

netstat -ano | findstr LISTENING

List all active ports listening for connections, including the Process ID (PID).

taskkill /F /FI "STATUS eq NOT RESPONDING"

Force kill all applications that are currently frozen or 'Not Responding'.

wmic path softwarelicensingservice get OA3xOriginalProductKey

Retrieve the OEM product key embedded in the motherboard firmware (BIOS/UEFI).

python3 -m http.server 8000

Instant Web Server. Serves current directory over HTTP. Useful for quick file transfers

powercfg /batteryreport

Generates a detailed HTML report of battery health, cycles, and capacity history in user folder

netsh wlan show profile name="SSID" key=clear

Reveal the saved Wi-Fi password for a specific network in plain text.

ipconfig /flushdns

Clears the DNS resolver cache, potentially resolving connectivity issues by forcing the system to retrieve fresh DNS information.

defrag /c /h /v /b /o

Defragments all volumes, optimizes boot files, includes TRIM for SSDs, and provides detailed output.

defrag /c /h /v /a

Analyzes fragmentation levels on all volumes (HDDs only) with detailed output, and can be compared using the GUI version in dfrgui

sfc /scannow

Scans and repairs corrupted or missing system files, ensuring system integrity and proper operation.

cleanmgr /sageset:1 cleanmgr /sagerun:1

Use /sageset:1 to configure and save specific cleanup options for Disk Cleanup, and /sagerun:1 to execute the cleanup based on those saved settings.

chkdsk /f /r

Fixes errors on the disk and recovers readable information from bad sectors, improving overall disk integrity and performance. Usually, this is a very slow operation.

chkdsk /scan

Scans the file system on the specified volume for errors without fixing them, allowing for a thorough examination of disk health.

winget repair [package-name or package-ID]

Repairs the specified installed application using winget. It verifies and attempts to fix issues with applications managed by winget. You can specify the application by either its name or ID. This works only on supported installations and may not be available for all applications (winget will display a message if unavailable). Requires Windows 10 version 1809 (build 17763) or later.

winget upgrade --all

Upgrades all updatable packages to their latest versions using winget. This only applies to winget updatable packages and may not include all installations. Requires Windows 10 version 1809 (build 17763) or later.

winget list

Lists all installed packages on the system using winget. The list shows only winget affected and updatable programs. Requires Windows 10 version 1809 (build 17763) or later.

dnf --assumeno install package1

Runs a DNF transaction that shows what would be done but aborts instead of applying changes, letting you preview packages to be installed or removed without modifying the system.

apt autoremove --purge

Removes packages that were automatically installed to satisfy dependencies and are no longer required, and with --purge also removes their configuration files; run apt clean afterward to clear cached package archives.

apt -s install package1 package2

Performs a simulated install showing packages that would be installed or removed without changing the system

apt remove --purge package1

Removes the package and its installed files, and with --purge also removes system-wide configuration files from /etc and dpkg's info so the package is fully removed.

apt --no-install-recommends --no-install-suggests package1 package2

Installs specified packages using apt while suppressing recommended and suggested packages, ensuring only required dependencies are pulled for a minimal installation. To disable this behavior system-wide, add the lines APT::Install-Recommends "false"; APT::Install-Suggests "false"; to /etc/apt/apt.conf (or drop files with those settings under /etc/apt/apt.conf.d/) so apt defaults to not installing recommends/suggests

MP4Box -info $VIDEO.mp4 2>&1 | grep RFC6381 | awk '{print $4}' | paste -sd , -

Inspects an MP4 file to find all RFC 6381 codec identifiers and formats them into a single, comma-separated string suitable for the 'codecs' attribute in an HTML5 video tag.

find ./.artwork/jpeg/ -type f \( -name "*.jpeg" -o -name "*.jpg" ! -name "*_optimized.jpeg" \) -exec bash -c 'magick -strip -quality 88 -verbose -limit thread 0 "$0" sixel:- > "${0%.*}.six"' '{}' \;

Finds all JPEG images in a specific directory, skipping any that are already optimized, then converts each image into the SIXEL graphics format for terminal display, saving the result as a .six file.

find . -type f -wholename '*.flac' -exec bash -c 'ffmpeg -hide_banner -loglevel error -nostats -y -i "$(eval "echo .meta/artwork/*video_cover_l.jpeg")" -i "${0}" -metadata title="$(metaflac --show-tag=TITLE "${0}" | cut -c7-)" -metadata artist="$(metaflac --show-tag=ARTIST "${0}" | cut -c8-)" -metadata album="$(metaflac --show-tag=ALBUM "${0}" | cut -c7-)" -metadata genre="$(metaflac --show-tag=GENRE "${0}" | cut -c7-)" -metadata encoded_by="FFmpeg" -q:v 8 -codec:v libvpx-vp9 -lossless 1 -preset slow -quality good -speed 0 -deadline best -codec:a libopus -b:a 160k -vbr on -compression_level 10 -pix_fmt yuv420p -threads 0 "./${0%.*}_vp9_opus_1080p.webm"' '{}' \;

Finds all FLAC files and converts each one into a WebM video that uses a static cover image for the video track, which is encoded losslessly with high-quality VP9 settings, while preserving all metadata

git ls-files . --exclude-standard --others

Shows a list of all untracked files that do not match any standard gitignore rules.

git ls-files . --ignored --exclude-standard --others

Shows a list of all files in the current directory that are untracked and match a pattern in a standard gitignore file.

Get-ChildItem -Path Cert:\CurrentUser\My | Select-Object - Property Subject, NotAfter

Displays the subject and expiration date for all certificates in the current user's personal certificate store.

git show b523b86 | grep -i 'JS'

Displays the full diff of a specific commit but filters the output to show only the lines containing a certain string.

git log -S "specific_variable_name"

Finds all commits where the number of occurrences of a specific string or code snippet changed (a "pickaxe" search).

lsof -p 1234

Shows every file, network socket, and library being used by a process with a specific PID (e.g., 1234).

dnf provides /usr/bin/ssh

Identifies the software package that installed a given file (e.g., /usr/bin/ssh).

dig +trace google.com

Performs a DNS lookup by querying the root servers and following the entire delegation path down to the authoritative nameserver.

openssl dgst -sha256 myfile

Computes and displays the SHA256 hash of a file, useful for verifying file integrity without needing a separate sha256sum tool.

truncate -s 5G large_dummy_file.img

Creates a sparse file of a specified size (e.g., 5 Gigabytes) almost instantly.

git bisect start BAD_COMMIT GOOD_COMMIT

Starts an interactive binary search between a known "good" and "bad" commit, allowing you to quickly pinpoint which change caused a regression.

iostat -dx 2

Displays detailed, per-disk I/O statistics (reads/writes per second, utilization) every 2 seconds.

nmap -p 22 --open 192.168.1.0/24

Scans the entire 192.168.1.0/24 subnet and lists only the hosts that have the specified TCP port (e.g., 22 for SSH) open.

podman inspect bfd59994e8f2

Shows low-level information about a container, such as its state, configuration, and network settings, in JSON format.

journalctl --unit=nginx.service --follow --output=json-pretty

Follows the logs for a specific systemd unit in real-time, formatting the output as human-readable JSON.

ss -tlpn 'sport = :8080'

Displays the process name and PID that is actively listening on a given TCP port (e.g., 8080).

php phpstan.phar --memory-limit=4096M analyse --level max '~/index.php'

Analyzes a specific PHP file for potential errors using the strictest rule set and a 4GB memory limit.

ionice -c 3 -n 7 mistat.py generate-all

Executes the mistat.py script with minimal I/O priority to reduce disk usage and prevent overwhelming the disk with high-volume I/O operations.

comm -23 mistat_v3.py mistat_v4.py

Compares two versions of a script and prints lines that are unique to the first version, showing what was removed or changed.

date -d '2025-06-13 08:22:00 UTC' +%s

Converts a specified UTC date and time into a UNIX timestamp (seconds since epoch)

find . -type f -wholename '*.flac' -exec bash -c 'DELAY_COMPENSATION=0.2; SMOOTHING_PX=2; FLAC_FILE="$0"; COVER_PATH=".meta/artwork/$(basename "${FLAC_FILE}" ".flac")-video_cover_l.jpeg"; BRIGHTNESS=$(magick "$COVER_PATH" -colorspace Gray -format "%[mean]" info:); VISUALISER_COLOR="white"; BRIGHTNESS_THRESHOLD=35000; if (( $(echo "$BRIGHTNESS > $BRIGHTNESS_THRESHOLD" | bc -l) )); then VISUALISER_COLOR="black"; fi; GEQ_FORMAT="r=r(X,Y):g=g(X,Y):b=b(X,Y):a=st(0,H/2*sin(X/W*PI));st(1,abs(Y-H/2));if(gt(ld(1),ld(0)),0,if(lt(ld(1),ld(0)-%s),alpha(X,Y),alpha(X,Y)*(ld(0)-ld(1))/%s))"; GEQ_FINAL=$(printf "$GEQ_FORMAT" "$SMOOTHING_PX" "$SMOOTHING_PX"); echo "Processing ${FLAC_FILE}. Cover brightness: $BRIGHTNESS. Using visualiser color: $VISUALISER_COLOR. Applying ${DELAY_COMPENSATION}s delay compensation. Applying ${SMOOTHING_PX}px edge smoothing."; ffmpeg -hide_banner -loglevel error -nostats -y -framerate 24 -i "$COVER_PATH" -i "$FLAC_FILE" -filter_complex "[0:v]scale=1920:1080,setsar=1[bg]; [1:a]asplit[a_out][a_viz]; [a_viz]asetpts=PTS-${DELAY_COMPENSATION}/TB[a_viz_shifted]; [a_viz_shifted]showwaves=s=1400x140:mode=cline:colors=${VISUALISER_COLOR}:draw=full:rate=24,format=rgba[waves_hr]; [waves_hr]scale=700:70:eval=init:flags=lanczos[waves]; [waves]geq='\''"$GEQ_FINAL"'\''[waves_faded]; [waves_faded]colorchannelmixer=aa=0.3[waves_transparent]; [bg][waves_transparent]overlay=(W-w)/2:910[outv]" -map "[outv]" -map "[a_out]" -metadata title="$(metaflac --show-tag=TITLE "${FLAC_FILE}" | cut -c7-)" -metadata artist="$(metaflac --show-tag=ARTIST "${FLAC_FILE}" | cut -c8-)" -metadata album="$(metaflac --show-tag=ALBUM "${FLAC_FILE}" | cut -c7-)" -metadata genre="$(metaflac --show-tag=GENRE "${FLAC_FILE}" | cut -c7-)" -metadata encoded_by="FFmpeg" -crf 45 -b:v 0 -codec:v libvpx-vp9 -cpu-used 0 -row-mt 1 -auto-alt-ref 1 -lag-in-frames 25 -g 250 -codec:a libopus -b:a 160k -vbr on -compression_level 10 -frame_duration 60 -application audio -pix_fmt yuv420p -threads 0 "./${FLAC_FILE%.*}_vp9_opus_visualiser_1080p.webm"' '{}' \;

This command automatically converts FLAC audio files into WebM videos. For each track, it uses the corresponding album art as a static background and overlays a custom audio visualiser. This transparent visualiser is styled as a pill-shape with faded edges, and its color is intelligently set to black or white to contrast with the brightness of the artwork. To ensure the visuals align perfectly with the sound, a delay is applied to the visualiser's audio stream for precise synchronization. Finally, all original metadata (like title, artist, and album) is transferred from the FLAC file to the new WebM video.

cuebreakpoints "Pohokolius - The Best Of.cue" | shnsplit -o flac -f "Pohokolius - The Best Of.cue" -t "%n-%t" "Pohokolius - The Best Of.flac"

Splits a single FLAC audio file into individual FLAC track files based on track timings defined in a CUE sheet.

for f in *.wav; do ffmpeg -i "$f" -hide_banner -loglevel error -nostats -vn -c:a libopus -b:a 24k -compression_level 10 -application audio -map_metadata 0 -metadata composer="" -metadata ENCODED-BY="" -metadata comment="" -metadata COMM="" -metadata encoded_by="FFmpeg$(ffmpeg -version | head -n1 | awk '{print $3}')" "${f%.wav}.opus"; done

Converts all .wav files in the current directory to mono Opus audio files with a 24kbps bitrate, optimized for speech using the 'audio' application, preserving metadata and adding encoding information, ideal for podcast audio.

for f in *.wav; do ffmpeg -i "$f" -hide_banner -loglevel error -nostats -ac 1 -c:a libmp3lame -q:a 8 -joint_stereo 1 -compression_level 9 -map_metadata 0 -metadata composer="" -metadata ENCODED-BY="" -metadata comment="" -metadata encoded_by="FFmpeg$(ffmpeg -version | head -n1 | awk '{print $3}')" -id3v2_version 3 "${f%.wav}.mp3"; done

Converts all .wav files in the current directory to mono MP3 files with a lower bitrate (variable, around 64-80kbps), optimized for speech, preserving metadata and adding encoding information, which is ideal for podcast audio.

for f in *.flac; do ffmpeg -i "$f" -ab 320k -map_metadata 0 -id3v2_version 3 "${f%.flac}.mp3"; done

Iterates through all .flac files in the current directory, converts each to MP3 with a constant audio bitrate of 320kbps, preserves metadata, and sets the ID3v2 tag version to 3.

find . -type f -perm -o+w -ls

Finds and displays detailed information about files within the current directory and its subdirectories that have world-writable permissions.

ip addr show | grep -Eo 'inet (addr:)?([0-9]{1,3}\.){3}[0-9]{1,3}' | grep -Eo '([0-9]{1,3}\.){3}[0-9]{1,3}'

Retrieves and prints the system's IPv4 address(es) by parsing the output of the `ip addr show` command.

systemctl list-timers --all

Displays a comprehensive list of all systemd timers, including both active and inactive ones, along with their last and next execution times.

find . -type f -size +100M -print0 | xargs -0 ls -lh | sort -h

Locates all files exceeding 100 megabytes in the current directory and its subdirectories, then lists them with human-readable sizes, sorted from smallest to largest.

lsof -i TCP:80

Displays all processes that have open network connections or are listening on TCP port 80.

ps -eo pid,comm,%mem,%cpu --sort=-%mem | head

Shows a list of running processes, sorted in descending order based on memory consumption, also displaying CPU usage.

find . -type f -printf '%T+\t%p\n' | sort -n | head -n 1

Locates and prints the timestamp and name of the oldest file within the current directory and its subdirectories.

journalctl --disk-usage

Displays the current amount of disk space being consumed by the systemd journal logs.

ps aux | awk '{print $1, $2, $3, $4, $11}' | sort -k 4 -r | head -n 10

Lists the top 10 processes currently using the most memory, showing user, PID, %CPU, %MEM, and command.

echo 'Secret' > ~/.secret_file; history -d $((HISTCMD-1))

Writes "Secret" to a file and immediately removes its record from the shell's history.

find "${HOME}/cats" \( -name "*.png" -o -name "*.gif"\) -exec touch -t "$(date +%Y%m%d)0100" {} \;

Finds all PNG and GIF files within the specified directory and sets their modification time to 1:00 AM of the current day.

for d in */; do XZ_OPT="-9e" tar -cvJf "${d%/}.tar.xz" "$d"; done

Creates a separate .tar.xz archive for each subdirectory within the current directory, using maximum compression (XZ level 9e). Includes verbose output.

for f in *.mp3; do echo "$f: $(soxi -B "$f")"; done

Loops through all MP3 files in the current directory and displays their average bitrate using the soxi command.

find . -name "*.eno" -print0 | tar -czvf eno-backup-$(date '+%Y-%m-%d_%H%M%S').tar.gz --null -T -

Finds files with the ".eno" extension, and creates a compressed tar archive with a timestamped filename.

ping google.com | awk '{ print strftime("[%Y-%m-%d %H:%M:%S]"), $0; fflush() }'

Prepends a live timestamp to each line of ping output. Requires GNU awk (strftime is a gawk extension, not in BSD awk). fflush() forces line-by-line output instead of buffered bursts.

ping google.com | ts '[%Y-%m-%d %H:%M:%S]'

Prepends a timestamp to each line of ping output, using the ts command from the moreutils package.

flatpak override --reset com.bitwig.BitwigStudio

Resets all overrides (such as permissions or configurations) for a specified Flatpak package to its default settings.

flatpak override --show com.bitwig.BitwigStudio

Displays the current overrides (such as permissions or configurations) applied to a specified Flatpak package.

xdg-settings get default-web-browser

Displays the currently set default web browser on the system.

flatpak mask --remove com.bitwig.BitwigStudio

Re-enables updates and upgrades for a previously masked Flatpak package, allowing it to be updated again.

flatpak mask

Lists all Flatpak packages that have been masked, preventing updates or installation.

flatpak mask com.bitwig.BitwigStudio

Prevents the specified Flatpak package from being updated or installed by masking it.

flatpak update --commit=d46e23d2d45efb8f9b5e38d60abbbeb17cce6ee3d8143918fa4d7f0708b4eee7 com.bitwig.BitwigStudio

Updates a package to a specific commit hash, useful for downgrading or pinning a package to a particular version.

flatpak remote-info --log flathub com.bitwig.BitwigStudio

Displays the installation log and metadata for the specified package from the remote repository (flathub).

SELECT user,host FROM mysql.user;

Retrieves a list of users and their associated hosts from the MySQL or MariaDB mysql.user table.

SHOW GRANTS FOR 'ABC'@'%';

Shows the privileges granted to a specific user ('ABC'@'%') in MySQL or MariaDB.

find . -maxdepth 1 -type f -name "*.flac" -exec bash -c 'sha256sum "$1" | sed "s|./||" > "$1.sha256"' _ {} \;

Finds FLAC files in the current directory, generates a SHA256 checksum for each file, and saves the checksum to a separate .sha256 file, truncating the ./ from the file path.

Get-Process notepad* | Stop-Process -Force

Forcefully kills all running Notepad instances (e.g., notepad.exe, notepad.exe_1) using PowerShell's Stop-Process cmdlet.

taskkill /F /IM ms-teams.exe

Forcefully kills the ms-teams.exe process (Microsoft Teams) using the /F flag to terminate it immediately.

tasklist | findstr /i "teams.exe"

Uses tasklist combined with findstr to check if teams.exe (Microsoft Teams) is currently running on the system.

systeminfo | find /i "original"

Uses systeminfo combined with find to filter and display the "Original Install Date" from the system information output.

(Get-Item "C:\Windows\system.ini").CreationTime

Fetches the creation date of the C:\Windows\system.ini file, which can be used as an indicator of the system installation date. Alternatively, you can use C:\Windows\inf\setupapi.dev.log or C:\Program Files\WindowsApps\ instead of C:\Windows\system.ini.

du -h

Calculates and displays the sizes of files and directories in a human-readable format (e.g., KB, MB, GB) in PowerShell

Get-ChildItem -File | ForEach-Object { $hash = Get-FileHash $_.FullName -Algorithm SHA256 "$($hash.Hash) $($_.FullName)" }

Computes the SHA256 hash for each file in a directory and outputs the hash alongside the file's full path.

1..4 | ForEach-Object { -join ((65..90) + (97..122) + (48..57) | Get-Random -Count 10 | % {[char]$_}) }

Generates random 10-character alphanumeric strings in PowerShell

php -S 127.0.0.1:8080 -t .

Starts a PHP built-in server on 127.0.0.1 (localhost) at port 8080, serving files from the current directory (.).

for file in *.heic; do magick "$file" "${file%.heic}.jpeg"; done

Converts all .heic files in the current directory to .jpeg format using ImageMagick (magick). In ImageMagick v7 and later, the convert command is deprecated, so you should use magick instead.

git remote rename origin codeberg

Renames an existing Git remote repository, changing the name of the remote from origin to codeberg in the current repository configuration.

git remote -v

Displays the URLs of remote repositories associated with the current Git project, showing both fetch and push URLs.

git diff --staged

Displays the differences between the staged changes and the last committed version, showing what has been modified and prepared for the next commit.

sox *.flac -n stat

Generates and displays detailed statistical information (such as duration, peak level, RMS, etc.) for each .flac file in the specified directory.

ffmpeg -i INPUT.flac -af loudnorm=I=${TARGET_INTEGRATED_LOUDNESS}:TP=${TARGET_TRUE_PEAK}:LRA=${TARGET_LOUDNESS_RANGE}:measured_I=${MEASURED_INPUT_INTEGRATED_LOUDNESS}:measured_TP=${MEASURED_INPUT_TRUE_PEAK}:measured_LRA=${MEASURED_INPUT_LOUDNESS_RANGE}:measured_thresh=${MEASURED_INPUT_THRESHOLD}:offset=${TARGET_NORMALIZATION_OFFSET}:linear=true OUTPUT.flac

Normalizes the loudness of a .flac file to specified target values, using measured input loudness statistics to ensure consistent output volume.

ffmpeg -i *.flac -af loudnorm=print_format=summary -f null -

Analyzes the loudness of .flac files and prints the summary of integrated loudness, true peak, loudness range, and threshold.

free -t -m

Shows memory usage in megabytes, including total, used, and free memory, with the -t flag for total memory.

free -t | tail -n+2 | awk '{($2>0) ? p=$3/$2*100.0 : p=0.0; print "Used " $1 "\t" p "%"}'

Calculates and prints the used memory percentage for each category from the free command output.

grep -E --color 'Mem|Cache|Swap' /proc/meminfo

Searches for and highlights lines containing "Mem", "Cache", or "Swap" in the /proc/meminfo file.

dconf dump / >~/.config/dconf/user.conf dconf load / <~/.config/dconf/user.conf

Backs up dconf settings to a file and restores them from the backup.

for f in *.flac; do sox -S "${f}" -r 44100 -b 16 "${f%.*}"_16bit_44100.flac; done

Resamples all FLAC files in the current directory to 16-bit depth and 44.1kHz sample rate.

for f in *; do ffmpeg -i "$f" -map 0 -map -0:s -codec copy "$f.mkv"; done

Removes all subtitle streams from video files in the current directory and saves them as MKV files.

for f in *; do ffmpeg -i "$f" -f mp4 -c:v libx265 -preset ultrafast -crf 24 -acodec aac "${f%.*}"_x265.mp4; done

Reencodes all video files in the current directory to a more efficient MP4 format using H.265 for video and AAC for audio.

gpgconf --list-dirs

Displays the directories used by GPG for configuration, keyring, and other data.

gpg --list-keys

Displays all the GPG keys available in the keyring.

gpgconf --kill gpg-agent

Terminates the GPG agent process to stop managing keys and cache.

git commit --amend

Modifies the most recent Git commit, allowing changes to the commit message or content.

git config --global tag.gpgSign true

Configures Git to automatically GPG sign all tags globally.

git config --global commit.gpgsign true

Sets Git to automatically GPG sign all commits globally.

git config --global user.signingkey ABCBCA

Configures the specified GPG key (ABCBCA) as the global signing key for Git commits.

git log --all --pretty=format:"%h - %an <%ae>"

Lists all Git commits with their abbreviated hash, author name, and email in a custom format.

ledger reg Expenses -S amount

Displays expense transactions sorted by amount using the ledger-cli command-line accounting tool for Plain Text Accounting (PTA).

ledger bal ^Expenses ^Income --invert

Shows the balances for accounts whose names start with "Expenses" and "Income", with inverted values, using the ledger-cli command-line accounting tool for Plain Text Accounting (PTA).

ledger -M register Assets -X EUR -n --no-rounding

Displays asset transactions in EUR (specifying currency/commodity) without rounding, using the ledger-cli command-line accounting tool for Plain Text Accounting (PTA).

ledger reg -b 09/01 -e 12/01 --subtotal

Displays a subtotal of transactions between the specified date range (MM/DD format, 09/01 to 12/01) using the ledger-cli command-line accounting tool for Plain Text Accounting (PTA).

ledger bal Expenses -H --flat -S -T

Shows the expense account balances in a flat format without headers, sorting by date and excluding totals, using the ledger-cli command-line accounting tool for Plain Text Accounting (PTA).

ledger register Expenses

Lists all transactions under the expense category, displaying detailed records with the ledger-cli command-line accounting tool for Plain Text Accounting (PTA).

ledger balance Assets --collapse

Displays the balances of asset accounts, collapsing them into a summarized view using the ledger-cli command-line accounting tool for Plain Text Accounting (PTA).

ledger balance income expenses --period "this month"

Shows the balance of income and expenses for the current month using the ledger-cli command, a command-line accounting tool for Plain Text Accounting (PTA).

#!/bin/sh # Simple logging script with date filtering, colorizing, and Todo.txt compatibility. TIMESTAMP=$(date "+%Y-%m-%d [%H:%M:%S]") LOG="${HOME}/.jnrl.log" CONTEXT="${CONTEXT:-20}" TODOTXT_TAG='+jnrl' # Ensure the log file exists touch "$LOG" # Colorize timestamp matches in log output grep_coloring() { grep --color=always -P "(\[[0-9]{2}:[0-9]{2}:[0-9]{2}|\])" "$@" } # Handle date range filtering based on OS type (BSD vs GNU date) if [ "$1" = "-d" ] && [ "$2" -ge 0 ] 2>/dev/null; then DATE_RANGE=$(date --date="$2 day ago" "+%Y-%m-%d" 2>/dev/null || date -v "-$2d" "+%Y-%m-%d") grep "$DATE_RANGE" "$LOG" | grep_coloring elif [ -z "$*" ]; then # Show last N lines if no arguments are provided tail -n "$CONTEXT" "$LOG" | grep_coloring else # Log the message with timestamp and Todo.txt tag, escaping special characters echo "${TIMESTAMP} - $(printf '%q' "$*") $TODOTXT_TAG" >> "$LOG" fi

Logs messages with timestamps, allows date range searches, highlights timestamps, adds Todo.txt tags (+jrnl), and supports BSD/GNU date formats.

cat <<EOF (*- { $@ } //\ v_/_ EOF

Uses a here-document (cat <<EOF) to print a customizable ASCII art message, with $@ representing passed arguments, and outputs a simple "Tux say!" design.

pwgen -Bnyc | head -c15

Uses pwgen to generate a secure, random password with no ambiguous characters, then limits the output to the first 15 characters.

shuf -n10 /usr/share/dict/words | tr -d '\n' | head -c15

Uses shuf to randomly select 10 dictionary words, removes newline characters with tr, and limits the output to the first 15 characters, creating a memorable password like "correct battery staple horse" obligatory xkcd reference: 936 - https://xkcd.com/936

openssl rand -base64 16

Uses openssl to generate 16 bytes of random data and encodes it in Base64 format, providing a random password.

openssl rand -hex 15 | sha256sum | head -c15 | cut -b -15

Uses openssl to generate 15 bytes of random data in hexadecimal, hashes it with SHA-256, then truncates the output to the first 15 characters to create a random password.

gpg --gen-random --armor 1 15 | head -c15

Uses gpg to generate 15 bytes of random data as a password, outputs it in ASCII armored format, and limits the output to 15 characters.

#!/bin/bash PODCAST_DOWNLOAD_DIR="${HOME}/Ресурси/Преузимања/Podcasts" if [ -e "$PODCAST_DOWNLOAD_DIR" ] && [ ! -z "$(command -v ffmpeg)" ]; then find "$PODCAST_DOWNLOAD_DIR" -type f -name '*.mp3' -execdir sh -c ' PODCAST_FILE="$1" PODCAST_FILE_LENGTH_IN_SECONDS="1800" if [[ ! $PODCAST_FILE =~ ^[0-9]{2}- ]]; then random_filename_string=$(tr -dc "a-zA-Z0-9" < /dev/urandom | head -c 3) ffmpeg -i "$PODCAST_FILE" -c:a libmp3lame -q:a 6 -f segment -segment_time ${PODCAST_FILE_LENGTH_IN_SECONDS} -map 0:a -map_metadata -1 "${random_filename_string}-%02d-${PODCAST_FILE##*/}" && rm "$PODCAST_FILE" fi ' sh {} \; fi

Verifies podcast directory and ffmpeg, slices long .mp3 files into 30-minute segments with random prefixes, renames them with 01-99 numbering, reduces file size, and removes originals

cd "${BACKUP_DESTINATION}" && export XZ_DEFAULTS="-9 -T 0" && tar cJf "${BACKUP_FILENAME}.tar.xz" "$TARGET_PATH" 2>/dev/null && tar -tf "${BACKUP_FILENAME}.tar.xz" 2>/dev/null && sha256sum "${BACKUP_FILENAME}.tar.xz" > "${BACKUP_FILENAME}.tar.xz.sha256" && chown -R ${OWNER_USERNAME}:${OWNER_USERNAME} "${BACKUP_DESTINATION}/${BACKUP_FILENAME}.tar.xz"

Performs a series of operations in sequence: navigates to the backup destination, sets compression options (XZ_DEFAULTS for max compression and multi-threading), creates a .tar.xz archive, verifies it, generates a SHA256 checksum, and sets ownership. Each step is dependent on the previous one (using &&), so if any operation fails, the process stops immediately.

if [ -z "$(pidof -x "$1")" ]; then "$1" & exit 0; else exit 1;fi

Checks if the process specified by the argument ($1) is running; if not, it starts the process in the background. Exits with 0 if successful, or 1 if the process is already running.

cat myfile.txt | tr -d '\n' | wc -c

Removes newlines from a file and counts the remaining characters using tr and wc -c

GOGC=10 hugo server --environment development --watch --disableFastRender --templateMetrics --templateMetricsHints --buildFuture --buildDrafts

Starts the Hugo server in development mode with specific options like watching for changes and enabling future/draft builds

find . -type d -exec du -h --max-depth=1 {} + 2>/dev/null | sort -rh | head -n "10" | awk -v highlighter="\033[1;32m" -v reset="\033[0m" '{gsub(/[0-9,.]+[MGK]|^0[[:space:]]/, highlighter "&" reset); print}'

Finds and lists the top 10 largest directories, highlighting their sizes, sorted in descending order

find . -type f -exec du -h {} + 2>/dev/null | sort -rh | head -n "10" | awk -v highlighter="\033[1;36m" -v reset="\033[0m" '{gsub(/[0-9,.]+[MGK]|^0[[:space:]]/, highlighter "&" reset); print}'

Finds and lists the top 10 largest files, highlighting their sizes, sorted in descending order

find . -type f -name "*.txt" -exec wc -l {} +

Finds all .txt files and counts the number of lines in each using wc -l

cat /bin/ls | hexdump -C | less

Displays the binary content of the ls command using hexdump, piped through less for pagination.

SELECT random_article_id FROM random_articles WHERE date = DATE('now') LIMIT 1

Retrieves a random article ID from the random_articles table for the current date in sqlite.

podman exec -d "$client_name" /bin/sh -c "if which apk > /dev/null; then /usr/bin/node_exporter; elif which apt-get > /dev/null; then /usr/bin/prometheus-node-exporter; fi"

Starts the appropriate Node Exporter based on the package manager (apk or apt-get) inside a podman container.

podman exec -d "$client_name" sh -c "/usr/sbin/sshd -D -e"

Runs the SSH daemon in the background inside a podman container, allowing remote connections.

podman exec "$client_name" sh -c "pkill sshd"

Kills the sshd process inside a running podman container to stop the SSH service.

podman exec "$client_name" sed -i '/^#\?PubkeyAuthentication /c\PubkeyAuthentication yes' /etc/ssh/sshd_config

Modifies the SSH configuration inside a podman container to enable public key authentication.

podman machine set my-machine --cpus 4 --memory 4096

Adjusts the CPU and memory resources for a specific podman machine (4 CPUs, 4GB memory).

podman machine init my-machine --cpus 2 --memory 2048

Creates a new podman machine with 2 CPUs and 2GB of memory.

podman container ls -a --filter name="$container" --format "{{.Names}}"

Displays the name of a specific container in podman using a custom filter and format.

podman auto-update

Updates all containers managed by podman to the latest available versions automatically.

podman image prune -a -f

Deletes all unused images in podman, freeing up disk space with forced confirmation.

curl --silent -L "$download_url" -o "$filepath"

Downloads a file from a URL to a specified path, suppressing output and following redirects.

git -C "~/my_project" log --pretty=format:'%H' --max-count 5

Displays the latest Git commit hashes from a specific project path, limiting the number of messages to a defined count.

python -m http.server 8899 --bind 127.0.0.1

Starts a simple HTTP server on port 8899, binding it to the localhost IP (127.0.0.1).

git --no-pager show -s --format="%an <%ae>"

Displays the author's name and email address from the latest Git commit.

journalctl --unit clamav-clamonacc --since today

Displays ClamAV logs for the clamav-clamonacc service since the start of today.

find . -type f -exec du -h {} + | sort -r -h | head -n 10

Finds and lists the top 10 largest files in the current directory, sorted by size.

cmark --to html --validate-utf8 --unsafe

Converts a Markdown file to HTML with UTF-8 validation and allows unsafe HTML elements.

inxi -v 3 -F -B -z -c 7

Shows comprehensive system details, including hardware, boot, and network info, with formatted output and obfuscated sensitive data.

mpv --loop --audio-display=no

Loops the media playback in MPV while disabling the audio visualizations.

nano --autoindent --backup --boldtext --mouse --nonewlines --nowrap --nohelp --multibuffer --quickblank --smarthome --constantshow --linenumbers --tabstospaces -T 2 --indicator --backupdir="~/.cache" some_file_i_wanna_create.txt

Launches Nano with specific options like auto-indentation, line numbers, tab-to-space conversion, and backup configuration.

w3m -no-cookie -no-graph -W

Starts the w3m browser without using cookies or displaying images, with text-only output.

elinks -anonymous 1 -no-home 1 -no-connect 1

Starts ELinks with anonymous browsing, no home directory usage, and no network connection.

curl -Is -H "Accept-Encoding: gzip,deflate,br" https://durad.xyz | grep -i "content-encoding"

Sends an HTTP request and checks the Content-Encoding header to see if the response is compressed (gzip, deflate, or br).

netstat -tupan

Shows active network connections, listening ports, and associated processes with detailed information.

ps aux | sort -nr -k 4 | head -5

Lists the top 5 processes consuming the most memory, sorted in descending order.

dumpe2fs -h /dev/root | grep -i created

Retrieves the installation date of the operating system by checking the filesystem creation time on /dev/root.

find -not -empty -type f -printf "%s\n" | sort -rn | uniq -d | xargs -I{} -n1 find -type f -size {}c -print0 | xargs -0 md5sum | sort | uniq -w32 --all-repeated=separate

Finds duplicate files faster by comparing file sizes first, then checksums, using multiple tools in combination.

find . ! -empty -type f -exec md5sum {} + | sort | uniq -w32 -dD

Finds and lists duplicate files in the current directory by comparing their MD5 checksums.

echo 'BUS=="usb", OPTIONS+="ignore_device"' > /etc/udev/rules.d/971-usb-lockdown.rules

Creates a udev rule to ignore USB devices by adding a custom rule to the /etc/udev/rules.d/ directory.

udevadm control --reload-rules && udevadm trigger

Reloads udev rules and triggers devices to apply the new rules.

cryptsetup benchmark

Measures the performance of various encryption algorithms using cryptsetup.

cat /dev/urandom | tr -dc 'a-zA-Z0-9' | fold -w 10 | head -n 4

Generates random alphanumeric usernames, each 10 characters long, using /dev/urandom.

journalctl -b2

Displays system logs from the second-to-last boot using journalctl.

for file in *; do zip -r ${file%.*}.zip $file; done

Recursively compresses each file in the current directory into its own ZIP archive.

pactl set-sink-volume @DEFAULT_SINK@ +2%

Increases the volume of the default audio sink by 2% using pactl.

smartctl -l selftest /dev/sdX

Displays the results of previous SMART self-tests for a specified disk.

smartctl -t short /dev/sdX

Initiates a short self-test on a specified disk to check its health using SMART.

smartctl -a /dev/sdX

Displays detailed SMART (Self-Monitoring, Analysis, and Reporting Technology) information for a specified disk.

find $DIR_PATH -type f -exec chmod 644 {} \;

Recursively changes the permissions of all files within a specified path to 644.

find $DIR_PATH -type d -exec chmod 755 {} \;

Recursively changes the permissions of all directories within a specified path to 755.

for f in *.ass; do ffmpeg -i "$f" -c:s srt "${f%.*}".srt; done

Converts .ass subtitle files to .srt format using ffmpeg.

for f in *.flac; do sox -S "${f}" -r 44100 -b 16 ./resampled/"${f%.*}"_16bit_44100.flac; done

Resamples .flac audio files to 16-bit, 44.1 kHz format and saves them to a new directory.

xsetroot -cursor_name left_ptr

Changes the cursor to the specified type (e.g., left_ptr) in the X server environment.

iw list

Displays detailed information about available wireless network interfaces on a system.

for file in *.html; do printf "$file\t$(cat $file | wc -c | xargs printf "%'d\n")\t$(gzip -9c $file | wc -c | xargs printf "%'d\n")\t$(brotli -cZ $file | wc -c | xargs printf "%'d\n")\n"; done | tee

Prints the sizes of .html files, comparing uncompressed, gzipped, and brotli-compressed sizes in a tabular format.

vboxsdl --startvm $VM_NAME

Starts a VirtualBox VM using the SDL (Simple DirectMedia Layer) interface for graphical display.

vboxmanage modifyvm Debian5 --nic1 bridged --cableconnected1 on --bridgeadapter1 eth0

Configures a bridged network adapter for a VirtualBox VM, connecting it to the host's eth0 interface.

vboxmanage hostonlyif remove vboxnet0

Removes a host-only network interface (e.g., vboxnet0) from VirtualBox.

vboxmanage storagectl $VM_NAME --name "IDE Controller" --add ide --controller PIIX4

Adds an IDE controller to a VirtualBox VM with the specified controller type (PIIX4).

vboxmanage modifyvm $VM_NAME --memory 1024 --vram 128 --accelerate2dvideo on --accelerate3d off --audio alsa --cpuexecutioncap 85 --ostype WindowsXP

Modifies the settings of a VirtualBox VM, including memory, video, audio, CPU, and OS type.

vboxmanage createhd --filename $VM_HDD_PATH --size 35000 --variant fixed

Creates a new fixed-size virtual disk of 35 GB at the specified path for use in VirtualBox.

vboxmanage registervm $VM_PATH

Registers an existing virtual machine in VirtualBox using the path to the VM configuration file.

vboxmanage createvm -name "Debian" -ostype "Debian" --register

Creates and registers a new virtual machine named "Debian" in VirtualBox with the specified OS type.

stat -c %a .bashrc

Displays the permissions of a file (in this case, .bashrc) in numeric format.

rfkill unblock all

Unblocks all wireless devices (Wi-Fi, Bluetooth, etc.) using the rfkill unblock all command to enable them for use.

ffmpeg -i concat:"input1.mp4|input2.mp4" output.mp4

Combines multiple video files (input1.mp4 and input2.mp4) into a single file (output.mp4) using FFmpeg's concat protocol.

/etc/init.d/alsa-utils reset 0

Resets the ALSA (Advanced Linux Sound Architecture) settings by running the alsa-utils reset 0 script, which can help resolve audio issues on Linux. Note: init.d scripts are typically used in older init systems, but if your system is still using init.d to manage services, this command would be relevant.

systemctl set-default graphical.target

Configures the system to boot into graphical mode by setting the default target to graphical.target using systemctl in a systemd-based environment.

flatpak remote-ls flathub | grep org.gtk.Gtk3theme

Searches and lists GTK3 themes available in the Flathub repository using flatpak remote-ls and filters results with grep for org.gtk.Gtk3theme.

ausearch -c 'hl2_linux' --raw | audit2allow -M my-hl2linux

Uses ausearch to search for SELinux audit logs related to hl2_linux (Half-Life 2) and generates a custom policy module (my-hl2linux) with audit2allow to allow necessary actions.

grub2-mkconfig -o /boot/grub2/grub.cfg

Creates or updates the GRUB2 configuration file (/boot/grub2/grub.cfg) on Fedora, CentOS, or RHEL systems based on the current system setup and available kernels.

sealert -a /var/log/audit/audit.log

Analyzes SELinux-related messages in the audit log (/var/log/audit/audit.log) using sealert to provide detailed explanations and troubleshooting advice.

fixfiles onboot

Ensures SELinux file contexts are corrected during boot by running fixfiles onboot, typically used after system changes or restoring file systems.

journalctl --vacuum-time=2weeks

Removes systemd journal logs older than 2 weeks using journalctl --vacuum-time=2weeks to free up disk space.

dmesg | grep -i ahci

Filters and displays AHCI-related messages from the kernel log (dmesg), useful for troubleshooting or checking storage controller status.

dd if=/dev/zero of=./largefile bs=7M count=256

Measures SSD write performance by creating a 1.8 GB file (largefile) using dd with a block size of 7MB, writing zeros to the disk.

restorecon -r -v /

Recursively restores the correct SELinux security contexts for all files and directories under the root (/) directory, ensuring proper security labeling using restorecon -r -v.

vnstat -u -i wlp6s0

Initializes or updates the vnStat database for the specified network interface (wlp6s0), enabling traffic monitoring.

vnstat --iflist

Displays a list of network interfaces available for monitoring with vnstat on a Linux system.

package-cleanup --oldkernels --count=5

Removes all but the 5 most recent kernel versions using package-cleanup --oldkernels --count=5 to free up disk space.

gsettings list-recursively | grep -i Epiphany

Displays all GNOME settings related to Epiphany (Web) by recursively querying gsettings and filtering results with grep.

echo 'installonly_limit=4' > /etc/yum.conf

Sets the installonly_limit to 4 in /etc/yum.conf, restricting the number of kernel versions to keep on the system.

dnf remove $(dnf repoquery --installed --latest-limit=-2 -q)

Removes all but the latest installed 2 versions of packages using dnf repoquery to find older versions and dnf remove to uninstall them.

echo "never" > /sys/kernel/mm/transparent_hugepage/defrag

Sets the transparent hugepage defragmentation behavior to "never" by writing never to /sys/kernel/mm/transparent_hugepage/defrag on Linux.

authconfig --disablefingerprint --update

Disables fingerprint authentication by running authconfig --disablefingerprint and updates the system configuration.

tracker status

Displays the current status of the Tracker daemon, which is used for indexing and searching files on GNOME-based systems.

tracker daemon -t

Runs the Tracker daemon, typically used for indexing and searching on GNOME-based systems, in test mode (-t) for debugging and testing purposes.

echo "blacklist firewire-core" >> /etc/modprobe.d/firewired.conf

Appends blacklist firewire-core to /etc/modprobe.d/firewired.conf on Linux, preventing the firewire-core module from loading.

SELECT * FROM categories ORDER BY name ASC;

Retrieves and displays all categories from the database, sorted by name in ascending order.

dnf grouplist -v

Displays a verbose list of all available package groups in DNF, including both installed and available groups.

qemu-img create -f qcow2 -o preallocation=off <disk-name> <disk-size>

Creates a new QCOW2 disk image with the specified disk name and size, disabling preallocation for faster creation.

virsh pool-destroy default

Destroys the default storage pool in virsh, effectively stopping it and removing its resources from active use.

virsh pool-dumpxml default > pool.xml

Dumps the XML configuration of the default storage pool in virsh to a file (pool.xml).

pkcon refresh force -c -1

Forces a refresh of the PackageKit cache, bypassing any cached data, with -c -1 to use the default repo.

sed -i 's/^.*KeepCache=.*$/KeepCache=false/' /etc/PackageKit/PackageKit.conf

Modifies the PackageKit.conf file to set KeepCache=false, disabling the package cache for PackageKit.

dnf clean all --releasever=F41

Clears all cached data for DNF, including metadata and packages, for the specified release version (F41).

gsettings set org.gnome.software download-updates false

Uses gsettings to disable automatic downloading of updates in GNOME Software by setting download-updates to false under the org.gnome.software schema.

chmod a+x ~/.local/share/gnome-boxes

Adds execute permissions to the ~/.local/share/gnome-boxes directory for all users.

gnome-extensions -e system-monitor

Enables the system-monitor extension in GNOME, adding system monitoring features to the GNOME Shell.

dnf config-manager --set-disabled fedora-modular

Disables the fedora-modular repository in DNF, preventing it from being used during package operations.

dnf module reset $MODULE_NAME

Resets a specified DNF module ($MODULE_NAME), reverting it to its default stream and removing any custom settings.

dnf module list --enabled

Displays all currently enabled DNF modules, which are sets of packages grouped for easy management, often used for specific software streams or configurations.

dnf list installed *.i*86

Displays a list of all installed 32-bit packages (matching *.i*86 pattern) using DNF.

perl -c somescript_or_module.pl

Verifies the syntax of the specified Perl script (somescript_or_module.pl) without executing it.

hwclock --hctosys

Sets the system time to the current hardware clock (real-time clock) time.

hwclock --systohc

Sets the hardware clock (real-time clock) to the current system time.

dnf install @container-tools -y

Installs the @container-tools group package using DNF, automatically agreeing to all prompts.

rpm-ostree --idempotent install gnome-shell-extension-caffeine

Installs the gnome-shell-extension-caffeine package with idempotency to ensure the command can be safely re-run.

freshclam

Updates the ClamAV virus definitions by running the update command.

dnf --setopt=strict=0 --setopt=install_weak_deps=False install nano

Installs the nano package while disabling strict mode and preventing the installation of weak dependencies.

find ~/logs ~/access-logs ~/tmp/{analog,awstats,webalizer,webalizerftp} -type f \( -name "*.log" -o -name "*.txt" -o -name "*.rs" -o -name "*90a3ac" \) -exec sed -i -E '/djura|dura|80a5ai3dd|pohokolius|--90a3ac/Id' {} +

Searches cPanel log files for specific keywords (e.g., "djura", "dura", etc.) and deletes any lines that contain them.

find ~/logs ~/access-logs ~/tmp/{analog,awstats,webalizer,webalizerftp} -type f \( -name "*.log" -o -name "*.txt" -o -name "*.rs" -o -name "*90a3ac" \) -exec grep -H -E 'djura|dura|80a5ai3dd|pohokolius|--90a3ac' {} \;

Searches for specific keywords (e.g., "djura", "dura", etc.) in various cPanel log files and displays all matching entries.

sed -i.bak -e '/^#ControllerMode = dual/s/^#//; /^ControllerMode = le/!s/^ControllerMode = dual$/ControllerMode = le/' -e '/^#AutoEnable=true/s/^#//; /^AutoEnable=false/!s/^AutoEnable=true$/AutoEnable=false/' /etc/bluetooth/main.conf

Modifies the /etc/bluetooth/main.conf configuration file to disable Bluetooth power-saving settings that can lead to poor or intermittent communication with devices, particularly low-power ones.

find . -type f | sed -rn 's|.*/[^/]+\.([^/.]+)$|\1|p' | sort | uniq -c | sort -rn

Finds and displays the most common file extensions in the current directory and subdirectories, counting occurrences of each type and sorting them by frequency.

echo '<device screen="0" driver="dri2"><application name="Default"><option name="vblank_mode" value="0"/></application></device>' > ~/.drirc

Disables vertical synchronization (V-Sync) in GNOME by modifying the ~/.drirc file, preventing the GPU from waiting for the monitor's refresh rate, potentially improving frame rates in certain applications but possibly introducing screen tearing.

cat /sys/kernel/debug/dri/*/radeon_pm_info

Displays detailed power management statistics for AMD Radeon GPUs, showing information such as current performance states, clock speeds, and power usage for various components like the GPU, memory, and display.

cat /sys/class/drm/card*/device/power_dpm_force_performance_level

Displays or modifies the DPM (Dynamic Power Management) performance level for AMD GPUs, which controls the power and performance state of the GPU. This setting can help optimize energy usage or force the GPU to operate at specific performance levels.

cat /dev/urandom > /dev/pcspkr

Sends random data from /dev/urandom to the PC speaker (/dev/pcspkr), generating continuous beeping or noise. This can be used for simple sound effects or to test the PC speaker functionality. Warning: this can produce loud and potentially high-pitched noise!

pacat /dev/urandom

Plays continuous white noise by streaming random data from /dev/urandom through PulseAudio using pacat. This can be used for various purposes such as masking background noise or testing audio output. Warning: this can produce loud and potentially unpleasant noise.

dd if=/dev/urandom of=/dev/null status=progress

Runs the dd command to read from /dev/urandom and discard the output, while showing a progress bar that updates in real-time. The status=progress option (available from GNU Coreutils 8.24 released in June 2015) provides a running status of how much data has been processed, useful for long-running data transfers.

echo -e "* hard nproc 2500\n@users hard nproc 3250\nroot hard nproc 3250\n* hard core 0\n* hard maxlogins 2" | sudo tee -a /etc/security/limits.conf

Adds custom resource limits to the /etc/security/limits.conf file, including process limits for users and root, disabling core dumps for all users, and restricting the maximum number of simultaneous logins per user to 2, ensuring better system resource management and security.

ulimit -aH

Shows the hard resource limits for the current user, such as maximum file size, number of open files, and maximum memory usage, using the ulimit command with the -aH option.

find . -type f \( -name "*.[Pp][Nn][Gg]" -o -name "*.[Jj][Pp]*[Gg]" -o -name "*.[Gg][Ii][Ff]" -o -name "*.[Ww][Ee][Bb][Pp]" \) -exec exiftool -overwrite_original -all= {} \;

This command searches for image files (*.png, *.jpg, *.jpeg, *.gif, *.webp) in the directory and its subdirectories and uses exiftool to strip all metadata from each file. The -overwrite_original flag ensures that the images are overwritten with metadata-free versions, which is useful for privacy, reducing file size, or preparing files for distribution.

find . -type f -iname '*' -exec exiftool -overwrite_original -all= {} \;

Finds all files in the current directory and subdirectories, and removes all metadata (such as EXIF, IPTC, XMP) from each file using exiftool, overwriting the originals.

find . -type f \( -name "*.[Pp][Nn][Gg]" -o -name "*.[Jj][Pp]*[Gg]" -o -name "*.[Gg][Ii][Ff]" -o -name "*.[Ww][Ee][Bb][Pp]" \) -exec exiv2 -da rm {} \;

Finds all image files (PNG, JPEG, GIF, WebP) in the current directory and subdirectories, and removes any EXIF metadata using exiv2, ensuring privacy by stripping image metadata.

find . -type f -iname '*' -exec exiv2 -da rm {} \;

Finds all files in the current directory and subdirectories and removes any EXIF metadata using exiv2, effectively stripping the metadata from images, PDFs, and other file types that support EXIF.

find . -name "*.[Jj][Pp]*[Gg]" -printf ' jpegoptim > %p\n' -exec jpegoptim -f --strip-none --overwrite --quiet {} \;

This command searches for JPEG files (*.jpg, *.jpeg, etc.) and uses jpegoptim to apply lossless optimization. The -f flag forces the optimization, --strip-none preserves all metadata, --overwrite replaces the original files with the optimized versions, and --quiet suppresses output for a smoother, silent operation.

find . -name "*.[Jj][Pp]*[Gg]" -printf ' jpegtran > %p\n' -exec jpegtran -optimize -copy all {} > {} \;

This command recursively searches for JPEG files (*.jpg, *.jpeg, etc.) and uses jpegtran with the -optimize option to apply lossless compression, reducing the file size without losing quality. The -copy all option ensures that all metadata (such as EXIF data) is preserved. The > operator overwrites the original files with the optimized versions.

find . -name "*.[Gg][Ii][Ff]" -printf ' gifsicle > %p\n' -exec gifsicle --batch --no-warnings --no-comments --optimize=3 {} \;

This command recursively searches for GIF files (*.gif or *.GIF) and uses gifsicle to apply advanced optimization (--optimize=3) while removing comments and warnings for a quieter process. The --batch flag ensures that all GIF files are processed in batch mode.

find . -name "*.[Pp][Nn][Gg]" -printf ' pngcrush > %p\n' -exec pngcrush -ow -rem alla -reduce -brute -q -warn {} \;

This command searches for PNG files (*.png or *.PNG) in the current directory and subdirectories, and applies lossless compression using pngcrush with options to remove unnecessary chunks (-rem alla), optimize file size (-reduce), and apply brute-force optimization (-brute). The -ow option overwrites the original files, while -q suppresses unnecessary output, and -warn shows warnings if any issues arise during the process.

find . -name "*.[Pp][Nn][Gg]" -printf ' optipng > %p\n' -exec optipng -preserve -clobber -nc -nb -o7 -zm1-9 -quiet {} \;

This command recursively locates all PNG files (*.png or *.PNG) and uses optipng to apply maximum optimization (-o7), varying compression levels (-zm1-9), and other options like preserving metadata (-preserve) and avoiding overwriting existing files (-nc). The -quiet option suppresses unnecessary output during optimization.

find . -name "*.[Pp][Nn][Gg]" -printf ' oxipng > %p\n' -exec oxipng -ao max -Z -q {} \;

This command recursively searches for PNG files (*.png or *.PNG) and uses oxipng to apply maximum compression (-ao max), lossless optimization (-Z), and quiet mode (-q) to reduce file sizes without losing image quality.

flatpak uninstall --unused

Uninstalls Flatpak applications and runtimes that are no longer needed, freeing up disk space by removing dependencies that are no longer required by any installed applications.

flatpak uninstall --delete-data org.gnome.TextEditor

Uninstalls the GNOME Text Editor (org.gnome.TextEditor) flatpak application and deletes its associated data, freeing up space and ensuring no leftover configuration or cache files remain.

qemu-img convert -f vdi -O qcow2 [VBOX-IMAGE.vdi] [KVM-IMAGE.qcow2]

Uses qemu-img to convert a VirtualBox disk image ([VBOX-IMAGE.vdi]) into the KVM-compatible QCOW2 format ([KVM-IMAGE.qcow2]), enabling the image to be used with KVM/QEMU virtual machines.

VBoxManage modifyhd [VDI] --resize [megabytes]

Resizes an existing VirtualBox disk image ([VDI]) to a new size, specified in megabytes, using the --resize option.

VBoxManage clonehd [old-VDI] [new-VDI] --variant Fixed

Clones an existing VirtualBox disk image ([old-VDI]) to a new one ([new-VDI]) with a fixed size using the --variant Fixed option, meaning the new disk will have a set size rather than dynamically expanding.

VBoxManage clonehd [old-VDI] [new-VDI] --variant Standard

Clones an existing VirtualBox disk image ([old-VDI]) to a new one ([new-VDI]) using the --variant Standard option, creating an exact copy of the original virtual hard disk.

avahi-browse -alr

Uses avahi-browse to list all available services (both local and remote) on the local network, including their types and instance names, in real-time.

firewall-cmd --add-service=http --permanent

Adds the HTTP service (port 80) to the allowed services in the firewall permanently using firewall-cmd, ensuring that the rule persists after a reboot.

firewall-cmd --add-service=http

Adds the HTTP service (port 80) to the list of allowed services in the firewall using firewall-cmd, enabling inbound HTTP traffic.

echo -e '[device]\nwifi.scan-rand-mac-address=yes\n\n[connection]\nwifi.cloned-mac-address=random\nethernet.cloned-mac-address=random\nconnection.stable-id=${CONNECTION}/${BOOT}' > /etc/NetworkManager/conf.d/00-macrandomize.conf

Configures NetworkManager to randomize the MAC address for Wi-Fi scans, cloned MAC addresses for connections, and assigns a stable ID for network connections on boot, helping improve privacy and prevent tracking.

echo 'none' > /sys/class/leds/ath9k_htc-phy0/trigger

Disables the LED trigger for Atheros-based wireless devices (e.g. using ath9k_htc driver) by setting the trigger to 'none'. This can prevent network performance issues caused by excessive power draw from the LED. Used this on TP-Link TL-WN721N WiFi dongle

logread -t | grep -iE '(warn|crit|err)'

Uses logread to scan OpenWRT kernel logs, filtering for and displaying lines containing warnings (warn), errors (err), or critical (crit) messages to quickly identify potential issues.

cat /sys/kernel/debug/iee*/phy*/airtime_flags

Displays the airtime flags (airtime_flags) for WLAN interfaces on Atheros-based devices in OpenWRT, useful for monitoring and managing airtime scheduling and prioritization for wireless clients.

cat /sys/kernel/debug/iee*/phy*/netdev:wlan*/stations/*/aql

Displays the Active Queue Length (AQL) setting for individual WLAN stations on ath79-based devices in OpenWRT, which is useful for monitoring and tuning wireless traffic management per station.

cat /sys/kernel/debug/iee*/phy*/aql_enable

Displays the current status of AQL (Active Queue Length) enable setting on ath79-based devices in OpenWRT, useful for tuning network performance and managing queue lengths for wireless traffic.

cat /sys/kernel/debug/iee*/phy*/netdev:wlan*/stations/*/peer_ps_state

Displays the power save state (peer_ps_state) for WLAN stations connected to ath79-based devices in OpenWRT, providing insight into the power management status of wireless clients.

cat /sys/kernel/debug/iee*/phy*/netdev:*/aqm

Displays the AQMs (Active Queue Management) settings for network devices under the /sys/kernel/debug/iee*/phy*/netdev:*/aqm path in OpenWRT, useful for network performance tuning and debugging.

find /sys/kernel/debug/iee*/phy* -name aqm

Searches for AQMs (aqm) configuration files in the OpenWRT /sys/kernel/debug/iee*/phy* path, which relate to Active Queue Management settings for network devices.

grep -iE '(BEAMFORME|ANTENNA)' /var/run/hostapd*.conf

Searches for BEAMFORME and ANTENNA settings in the hostapd configuration files on OpenWRT. In some cases, you can expect output such as beamforming capabilities (SU-BEAMFORMER, MU-BEAMFORMER), antenna patterns, and OFDMA settings like he_su_beamformer and he_mu_beamformer.

nmap -p0-65535 127.0.0.1 -T5

Uses nmap to scan all ports (0-65535) on the local machine (127.0.0.1) with aggressive timing (-T5) for faster results.

netstat -lntu

Uses netstat to show all listening TCP, UDP, and UNIX domain sockets, along with their state and associated ports.

ss -lntu

Uses the ss tool to show all listening TCP, UDP, and UNIX domain sockets, providing detailed information about their states and ports.

hdsentinel -solid | awk '{print "[\t" $3 "% \t] "$5}'

Uses hdsentinel to retrieve SSD health and usage information, then formats the output to show the health percentage and corresponding attribute name.

fstrim -v /

Performs a manual trim operation on the root filesystem, freeing unused blocks on SSDs to improve performance, with verbose output. Warning: Be cautious when running fstrim on the root filesystem, as incorrect use or trimming certain filesystems can potentially lead to data loss in some configurations.

grep . /sys/block/sd?/queue/scheduler

Searches and outputs the I/O scheduler settings for all block devices (e.g., /dev/sda, /dev/sdb) by reading their respective /queue/scheduler files.

for f in /sys/block/sd?/queue/scheduler; do printf "$f is "; cat $f; done

Iterates over all block devices (e.g., /dev/sda, /dev/sdb) and prints the current I/O scheduler used for each device.

grep . /sys/block/sd?/queue/rotational

Displays whether each block device (/dev/sda, /dev/sdb, etc.) is rotational (HDD) or non-rotational (SSD) by checking the /queue/rotational property.

for f in /sys/block/sd?/queue/rotational; do printf "$f is "; cat $f; done

Checks and displays whether each block device (e.g., /dev/sda, /dev/sdb) is rotational (HDD) or non-rotational (SSD) by reading from /sys/block/*/queue/rotational.

dmesg | grep -i 'ata link up'

Searches the system log for messages related to ATA link status, specifically looking for "ATA link up" events.

seq 3 | xargs -P0 -n1 md5sum /dev/zero

Runs a parallel MD5 hash calculation on /dev/zero three times, stressing the CPU with multiple concurrent processes using xargs -P0.

yes > /dev/null &

Stresses the CPU by running the yes command in the background, which continuously outputs "y" to /dev/null without consuming disk space.

dd if=/dev/urandom | bzip2 -9 >> /dev/null

Tests CPU performance by compressing random data from /dev/urandom using the bzip2 compression algorithm at maximum level (-9), discarding the output.

dd if=/dev/zero of=/dev/null

Measures the raw disk write speed by writing zeros to /dev/null, effectively testing the system's I/O throughput.

watch -n 2 cpupower monitor

Displays real-time CPU power and frequency data, updating every 2 seconds using cpupower monitor.

perf stat -a sleep 2

Gathers and displays performance statistics (e.g., CPU usage, cache hits) for the entire system while the system is idle for 2 seconds.

@reboot echo -n $USER_DEFINED > /sys/devices/system/cpu/cpufreq/ondemand/up_threshold

Sets the up_threshold for the CPU's ondemand governor to a user-defined value on system startup.

crontab -e -u pretzel

Opens the crontab file for the user pretzel, allowing you to schedule tasks for that user.

echo SUBSYSTEM=="module", ACTION=="add", KERNEL=="acpi_cpufreq", RUN+=" /bin/sh -c ' echo -n $USER_LIMIT > /sys/devices/system/cpu/cpufreq/ondemand/up_threshold ' " > /etc/udev/rules.d/50-scaling-governor.rules

Creates a udev rule that automatically sets the up_threshold for the CPU's ondemand governor when the acpi_cpufreq module is loaded.

echo -n $USER_LIMIT > '/sys/devices/system/cpu/cpufreq/ondemand/up_threshold'

Sets the up_threshold value for the CPU's ondemand governor to control when to increase CPU frequency based on load.

cpupower -c $CPU_CORES frequency-set -g performance

Sets the specified CPU cores (defined by $CPU_CORES) to performance mode for maximum frequency.

cpupower frequency-set -g performance

Configures the CPU to run at its maximum frequency for optimal performance.

cat /sys/devices/system/cpu/cpufreq/boost

Displays whether CPU frequency boosting is enabled or disabled on the system.

lscpu

Provides a summary of the system's CPU architecture, including core count, threads, and architecture type.

cat /proc/cpuinfo

Shows detailed information about the system's CPU, including model, cores, and clock speed.

glxinfo | grep memory

Extracts and shows memory-related details (e.g., video memory) for the GPU from the glxinfo output.

lspci -vvv | grep modules

Shows the kernel modules associated with PCI devices on the system.

lsusb -vs 006:001

Displays verbose details about the USB device located at 006:001.

lspci -vs 0a:00.0

Displays verbose information about the PCI device located at 0a:00.0.

lspci | grep VGA

Shows information about the VGA (graphics) device(s) on the system.

find ~/logs/{daily,monthly,weekly} -type f \( -name "*.log" -o -name "*.txt" \) | xargs sed -i -E '/monday\|tuesday/Id'

Searches log and text files in daily, monthly, and weekly directories, and deletes lines containing 'monday' or 'tuesday', case-insensitively.

find . -type f -size +50000k -exec cp -nv {} ./ \;

Finds files larger than 50MB and copies them to the current directory, showing verbose output.

find . -type f -name "*.log" -mtime +10 | xargs grep -iEn "(Error 403|Error 404)"

Finds .log files modified more than 10 days ago and searches for "Error 403" or "Error 404" within them.

find . -maxdepth 1 -type f -name "*apache*" -mtime +10 -exec echo {} \;

Finds and lists files in the current directory containing "apache" in the name, modified more than 10 days ago.

find . -iname "*.jpeg" -execdir mv -i '{}' cover.jpeg \;

Finds all .jpeg files (case-insensitive) and renames each to cover.jpeg in its respective directory, with confirmation.

find . -name "*.pdf" -exec cp {} ~/Documents \;

Searches for all .pdf files in the current directory and subdirectories, then copies them to ~/Documents.

sed -i 's/^.*NAutoVTs=.*$/NAutoVTs=2/' /usr/lib/systemd/logind.conf

Changes the value of "NAutoVTs" to 2 in /usr/lib/systemd/logind.conf file, modifying it in place.

sed -i 's/^String=.*$/New String = 22/g'

Replaces lines starting with "String=" with "New String = 22" in a file, modifying it in place.

dmidecode | awk '/(\t)+Size/{$1=""; print $0 }'

Filters the output of dmidecode to show memory size details, removing the first field from matching lines.

awk '/(\t)+Size/{$1=""; print $0 }'

Finds lines with "Size" preceded by tabs, removes the first field, and prints the rest.

grep -R 'search-string' ~/Some/Path/

Searches for 'search-string' in all files under the specified directory and its subdirectories.

grep -i -B 3 -A 5 'something something'

Finds 'something something' and shows 3 lines before and 5 lines after each match, case-insensitively.

grep -iE '(Word1|Word2|Word3)'

Searches for any of the specified words (word1, word2, or word3) in a case-insensitive manner.

awk -v SEPARATOR="," '{print $1 " " SEPARATOR " " $2 " " SEPARATOR " " $3}'

Adds the specified separator (a comma) between the printed fields ($1, $2, and $3) in the output.