I've been in the weird space of on-prem "cloud" infrastructure (mostly kubernetes) for the last seven years but I've been doing infra, middleware, and devops for more than twenty years and have my own way of working that's nearly GUI-free.

Tools I use every single day:

• tmux
• The one true editor and org-mode.
• The other one true editor.
• Bash, sed, awk, and the indispensable Shellcheck.
• Munging data with
  • jq and jiq for JSON.
  • yq similar to jq but processes YAML, JSON, XML, and TOML.
  • mlr is like awk, sed, cut, join, and sort all in one for CSV and TSV.
• curl and httpie.
• ag (the Silver Searcher) out of habit but ripgrep is awesome too.

Less often but very useful:

• socat a swiss army knife for sockets.
• ansible
• terraform

Languages, because I write my own tools:

• Go, a lot of it and I still don't like it.
• Python, and I tolerate it (Perl is still better for getting things done but lost mind share).
• Rust, and I like it.
• Elixir, and I love it.
• Guile and Janet when nobody's looking and I don't have to share (though the Nix folks don't mind me...).