Cheat sheet
crontab and /etc/cron.* cheat sheet
Where cron jobs live on Linux: user crontabs, /etc/crontab, /etc/cron.d and the cron.hourly, daily, weekly and monthly folders, run-parts naming rules and anacron.
linux
Cheat sheet
cron cheat sheet
Schedule jobs with cron: the five-field syntax, special strings, where crontabs live, the environment trap, logging, locking and one-off jobs with at.
Cheat sheet
Bash scripting cheat sheet
Write Bash scripts that fail loudly and clean up after themselves: strict mode, quoting, tests, loops, arrays, functions, traps and getopts.
Cheat sheet
awk cheat sheet
Split, filter, sum and reformat columns with awk: fields, separators, conditions and the one-liners I use on logs and command output.
Cheat sheet
apt vs dnf cheat sheet
The same package tasks side by side on Debian/Ubuntu (apt, dpkg) and RHEL, Rocky and Fedora (dnf, rpm): install, search, hold, history and repos.
Cheat sheet
/dev/null, /dev/zero and /dev/urandom cheat sheet
What Linux's special files do and how to use them: discard output, make test and swap files, wipe disks, generate random data and secrets, and test disk speed.
Cheat sheet
tar cheat sheet
Create, list, extract and compress archives with tar: the flags I actually use, with gzip, xz and zstd.
