About

I am an independent developer. I write about the Linux command line: how to put pipes together, what an awk or sed one-liner is really doing, when a systemd timer beats cron, how to keep a shell script from eating the wrong directory, and how to tidy up ssh config and dotfiles.

These are notes, not a course. Each one starts from something that went wrong on a real machine, gets reduced to a few commands I have run, and stops when the commands are explained. If a command behaves differently on macOS or BSD, I say so.

I will not tell you who I am, and there is no photo or employer to look up. What matters is whether the commands work. If one of them does not, write to me at shell@pipeandgrep.space and I will fix the note.

Topics I keep coming back to

• Composing pipelines and reading their output stage by stage
• awk and sed, the small useful parts
• systemd timers, units and journal commands, compared with cron
• ssh config: host aliases, ProxyJump, ControlMaster
• Safe shell scripting: strict mode, quoting, traps
• Dotfiles: keeping them in a repository and linking them into place