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
Cheat sheets
Compact, regularly updated references for the tools I use every day.
Cheat sheet
jq cheat sheet
Filter, reshape and summarise JSON on the command line with jq: selectors, select, map, group_by and the flags for scripts.
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
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 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 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 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
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.
Cheat sheet
Network debugging cheat sheet
Find where a Linux network problem is: DNS, routing, ports, firewalls, TLS or packet loss, with dig, ip, ss, nc, mtr, curl and tcpdump.
Cheat sheet
Regex cheat sheet
Regular expressions for grep, sed and awk: the syntax, how basic, extended and Perl-style regex differ, and patterns for IPs, dates and log lines.
Cheat sheet
sed cheat sheet
Find and replace, delete and print lines with sed, and edit config files in place safely, with the GNU and macOS differences.
Cheat sheet
Shell shortcuts cheat sheet
Move faster in Bash: readline keys, history search and expansion, brace expansion, globbing and the small tricks that save typing.
