166 commands · 10 cheat sheets · Linux

Processes, Services, and System master quick reference

Browse 166 commands from 10 focused cheat sheets on page 1 of 1. Each example opens its matching detailed section.

Processes, Services, and System · 16 commands

Core Dumps, strace, and Linux Debugging Cheat Sheet

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UseSyntaxExamples
List recent core dumpscoredumpctl list --since today --no-pagerView examples
Inspect one crashcoredumpctl info 4242 --no-pagerView examples
Filter by executablecoredumpctl list COREDUMP_EXE=/usr/local/bin/app \ --no-pagerView examples
Extract a core safelyumask 077; coredumpctl dump 4242 --output=app.coreView examples
Open latest matching dumpcoredumpctl debug /usr/local/bin/appView examples
Produce a batch backtracegdb --nx --batch --quiet -ex 'thread apply all bt full' \ /usr/local/bin/app app.coreView examples
Inspect core resource limitulimit -cView examples
Inspect kernel core handlersysctl kernel.core_patternView examples
Trace a new commandstrace -f -tt -T -s 256 -o trace.log -- \ /usr/local/bin/app --checkView examples
Trace file and network callsstrace -f -e trace=%file,%network -o trace.log -- \ /usr/local/bin/app --checkView examples
Attach to a processsudo strace -f -p 4242 -e trace=%file -o trace.logView examples
Summarize system callsstrace -f -c -- /usr/local/bin/app --checkView examples
Read a kernel stacksudo cat /proc/4242/stackView examples
Inspect process statuscat /proc/4242/statusView examples
Record mapped objectscat /proc/4242/mapsView examples
Read an ELF build IDreadelf -n /usr/local/bin/app | sed -n '/Build ID/p'View examples

Processes, Services, and System · 16 commands

Linux Boot and initramfs Diagnostics Cheat Sheet

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Show effective kernel argumentscat /proc/cmdlineView examples
Inspect boot loader statusbootctl statusView examples
Identify the running kerneluname -rView examples
List recorded bootsjournalctl --list-bootsView examples
Read previous boot errorsjournalctl --boot=-1 --priority=warning --no-pagerView examples
Read current kernel boot logjournalctl --dmesg --boot --no-pagerView examples
Summarize boot timesystemd-analyze timeView examples
Show critical chainsystemd-analyze critical-chainView examples
Rank unit activation timesystemd-analyze blameView examples
Inspect initrd dependenciessystemctl list-dependencies initrd.targetView examples
List a dracut imagelsinitrd /boot/initramfs-$(uname -r).imgView examples
List an initramfs-tools imagelsinitramfs /boot/initrd.img-$(uname -r)View examples
Print detected dracut argumentsdracut --print-cmdlineView examples
Inspect a newly built imagelsinitrd /tmp/initramfs-test.imgView examples
Boot to emergency targetsystemd.unit=emergency.targetView examples
Pause in dracut initramfsrd.break=pre-mountView examples

Processes, Services, and System · 14 commands

Linux Kernel Modules and sysctl Cheat Sheet

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Show running kerneluname -rView examples
List loaded moduleslsmodView examples
Inspect module metadatamodinfo e1000eView examples
Simulate module loadsudo modprobe --dry-run --verbose e1000eView examples
Load a modulesudo modprobe e1000eView examples
Remove a module safelysudo modprobe --remove e1000eView examples
Inspect effective modprobe configmodprobe --show-configView examples
List boot-load entriessystemd-analyze cat-config modules-load.dView examples
Read one sysctlsysctl vm.swappinessView examples
Change a runtime sysctlsudo sysctl -w vm.swappiness=10View examples
Check a staged sysctl filesystemd-analyze cat-config sysctl.dView examples
Apply system sysctl filessudo sysctl --systemView examples
Inspect kernel messagesjournalctl --dmesg --boot --no-pagerView examples
Read live module parametersfind /sys/module/e1000e/parameters -maxdepth 1 -type f \ -printView examples

Processes, Services, and System · 16 commands

Linux Package Management Cheat Sheet

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Search APT packagesapt search --names-only nginxView examples
Inspect APT metadataapt show nginxView examples
Search DNF packagesdnf search nginxView examples
Inspect DNF metadatadnf info nginxView examples
Refresh APT indexessudo apt updateView examples
Upgrade APT packagessudo apt upgradeView examples
Install with APTsudo apt install nginxView examples
Check DNF updatesdnf check-upgradeView examples
Upgrade with DNFsudo dnf upgradeView examples
Install with DNFsudo dnf install nginxView examples
Search Flatpak appsflatpak search org.gnome.TextEditorView examples
Install a Flatpak appflatpak install flathub org.gnome.TextEditorView examples
List package filesdpkg -L nginxView examples
Verify RPM filesrpm -V nginxView examples
Remove an APT packagesudo apt remove nginxView examples
Inspect DNF transactionsdnf history listView examples

Processes, Services, and System · 19 commands

Linux Processes Cheat Sheet

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List all processesps -efView examples
List your processesps -u "$USER" -o pid,ppid,stat,%cpu,%mem,commView examples
Inspect one PIDps -p 4242 -o pid,ppid,user,stat,lstart,cmdView examples
Show a process treeps -ef --forestView examples
Monitor processes livetopView examples
Find an exact namepgrep -a -x nginxView examples
Search full commandspgrep -a -u "$USER" -f "python3 -m http.server"View examples
Start a background jobpython3 -m http.server 8000 >server.log 2>&1 &View examples
Capture the latest PIDserver_pid=$!View examples
List shell jobsjobs -lView examples
Resume in foregroundfg %1View examples
Resume in backgroundbg %1View examples
Wait for a child processwait "$server_pid"View examples
Keep a command runningnohup python3 -m http.server 8000 >server.log 2>&1 &View examples
Request terminationkill -TERM 4242View examples
Force terminationkill -KILL 4242View examples
Signal an exact namepkill -TERM -x nginxView examples
Start with lower prioritynice -n 10 gzip archive.tarView examples
Change process priorityrenice -n 5 -p 4242View examples

Processes, Services, and System · 16 commands

Linux Time Synchronization and chrony Cheat Sheet

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Show synchronization statechronyc trackingView examples
List source selectionchronyc -n sources -vView examples
Show source statisticschronyc -n sourcestats -vView examples
Count source activitychronyc activityView examples
Wait for bounded accuracychronyc waitsync 60 0.01 0.1 10View examples
Explain source statechronyc selectdata -aView examples
Refresh source addressessudo chronyc refreshView examples
Mark sources onlinesudo chronyc onlineView examples
Collect measurements quicklysudo chronyc burst 4/4View examples
Step remaining correctionsudo chronyc makestepView examples
Print parsed configurationsudo chronyd -p -f /etc/chrony.confView examples
Configure an NTP poolpool time.example.net iburst maxsources 4View examples
Limit startup steppingmakestep 1.0 3View examples
Enable RTC synchronizationrtcsyncView examples
Read leap seconds from tzdataleapsectz right/UTCView examples
Persist NTS statentsdumpdir /var/lib/chronyView examples

Processes, Services, and System · 17 commands

logrotate and Linux Log Retention Cheat Sheet

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Debug a configurationsudo logrotate --debug /etc/logrotate.confView examples
Run verboselysudo logrotate --verbose /etc/logrotate.confView examples
Test with isolated statesudo logrotate --state /run/app-logrotate.state \ --verbose /etc/logrotate.d/appView examples
Force a rotationsudo logrotate --force /etc/logrotate.d/appView examples
Rotate by sizesize 100MView examples
Cap between intervalsmaxsize 500MView examples
Keep archive generationsrotate 14View examples
Expire old archivesmaxage 90View examples
Use sortable date suffixesdateextView examples
Compress archivescompressView examples
Delay compressiondelaycompressView examples
Create replacement securelycreate 0640 app admView examples
Run scripts oncesharedscriptsView examples
Signal the writerpostrotateView examples
Copy then truncate in placecopytruncateView examples
Drop rotation identitysu app admView examples
Inspect rotation schedulingsystemctl status logrotate.timer logrotate.service \ --no-pagerView examples

Processes, Services, and System · 23 commands

systemd Services and Journal Cheat Sheet

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List loaded servicessystemctl list-units --type=serviceView examples
List installed unit filessystemctl list-unit-files --type=serviceView examples
Inspect service statussystemctl status nginx.serviceView examples
Test active statesystemctl is-active --quiet nginx.serviceView examples
Read unit propertiessystemctl show nginx.service \ --property=ActiveState,SubState,MainPIDView examples
Show unit sourcesystemctl cat nginx.serviceView examples
Show dependenciessystemctl list-dependencies nginx.serviceView examples
Start a servicesudo systemctl start nginx.serviceView examples
Stop a servicesudo systemctl stop nginx.serviceView examples
Restart a servicesudo systemctl restart nginx.serviceView examples
Reload service configurationsudo systemctl reload nginx.serviceView examples
Enable and startsudo systemctl enable --now nginx.serviceView examples
Disable and stopsudo systemctl disable --now nginx.serviceView examples
Reload unit definitionssudo systemctl daemon-reloadView examples
Create a drop-in overridesudo systemctl edit nginx.serviceView examples
Read one unit's journaljournalctl --unit=nginx.service --no-pagerView examples
Limit to current bootjournalctl --boot=0View examples
Read previous bootjournalctl --boot=-1View examples
Filter by timejournalctl --since='1 hour ago' --until=nowView examples
Filter error prioritiesjournalctl --priority=err --boot=0View examples
Follow a unit livejournalctl --follow --unit=nginx.serviceView examples
Emit JSON recordsjournalctl --unit=nginx.service --output=json --lines=20View examples
Read kernel messagesjournalctl --dmesg --boot=0View examples

Processes, Services, and System · 15 commands

systemd Timers and Scheduled Jobs Cheat Sheet

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List timerssystemctl list-timers --allView examples
Inspect one timersystemctl status backup.timerView examples
Read timer propertiessystemctl show backup.timer -p NextElapseUSecRealtime -p \ LastTriggerUSec -p TriggersView examples
Validate a calendarsystemd-analyze calendar 'Mon..Fri 02:00'View examples
Calendar scheduleOnCalendar=Mon..Fri *-*-* 02:00:00View examples
Catch a missed runPersistent=trueView examples
Delay after bootOnBootSec=15minView examples
Delay after activationOnUnitActiveSec=6hView examples
Set timing accuracyAccuracySec=1minView examples
Spread startsRandomizedDelaySec=30minView examples
Keep host delay stableFixedRandomDelay=trueView examples
Select activated unitUnit=backup.serviceView examples
Enable and start timersudo systemctl enable --now backup.timerView examples
Test work directlysudo systemctl start backup.serviceView examples
Read job logsjournalctl --unit=backup.service --since=todayView examples

Processes, Services, and System · 14 commands

udev Rules and Linux Device Events Cheat Sheet

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Inspect a deviceudevadm info --query=all --name=/dev/sdbView examples
Walk parent attributesudevadm info --attribute-walk --name=/dev/sdbView examples
Resolve sysfs pathudevadm info --query=path --name=/dev/sdbView examples
Monitor kernel and udev eventsudevadm monitor --kernel --udev --propertyView examples
Filter event monitoringudevadm monitor --udev --property \ --subsystem-match=blockView examples
Verify rule syntaxudevadm verify /etc/udev/rules.d/70-backup-disk.rulesView examples
Test rule evaluationudevadm test --action=add /sys/class/block/sdbView examples
Test a builtinudevadm test-builtin blkid /sys/class/block/sdbView examples
Reload rulessudo udevadm control --reloadView examples
Preview a trigger scopeudevadm trigger --dry-run --verbose \ --subsystem-match=blockView examples
Retrigger one devicesudo udevadm trigger --action=change \ /sys/class/block/sdbView examples
Check the event queueudevadm settle --timeout=10View examples
Read udev daemon logsjournalctl --unit=systemd-udevd --boot --no-pagerView examples
Export the udev databaseudevadm info --export-dbView examples
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