Cheat sheet
mdadm cheat sheet
Linux software RAID with mdadm: create arrays, read /proc/mdstat, replace a failed disk, grow or change level, assemble after problems, and set up monitoring.
linux
Cheat sheet
Linux RAID cheat sheet
Software RAID with mdadm and the hardware RAID CLIs (storcli, perccli, ssacli): create arrays, check health, replace a failed disk, rebuild and monitor.
Cheat sheet
Linux processes cheat sheet
Find, inspect, signal and prioritise processes on Linux: ps, top, kill and its signals, jobs, nohup, nice, ionice and /proc.
Cheat sheet
Linux pipes cheat sheet
How pipes, redirects, xargs and tee fit together, plus the one-liners I use most: old files, top IPs, sort | uniq -c and friends.
Cheat sheet
Linux permissions cheat sheet
Read and set Linux file permissions: chmod in both notations, chown, umask, setuid, setgid, the sticky bit, ACLs and file attributes.
Cheat sheet
Linux disks cheat sheet
Check space, find what fills a disk, inspect block devices, mount filesystems, edit fstab safely and grow LVM volumes and partitions online.
Cheat sheet
journalctl cheat sheet
Read and filter the systemd journal: by unit, boot, time, priority and field, follow live logs, change the output format, and control the journal's size and persistence.
Cheat sheet
head and tail cheat sheet
Show the first or last lines or bytes of a file, follow logs that rotate, skip headers and cut out a range of lines with head and tail.
Cheat sheet
grep cheat sheet
Search text and logs with grep: the flags for context, recursion, regular expressions and counting, plus when to reach for ripgrep.
Cheat sheet
find cheat sheet
Find files by name, type, size, age and permissions, and act on them safely with -exec, -delete and xargs.
Cheat sheet
Disk full cheat sheet
Why a Linux disk says it's full and how to fix it: find what uses the space, free space held by deleted files that are still open, and fix running out of inodes.
Cheat sheet
curl cheat sheet
HTTP from the terminal with curl: headers, methods, JSON APIs, auth, downloads, TLS checks and timing a request phase by phase.
