less: tune flags, especially for systemd/journalctl

TODO.md

@@ -50,8 +50,6 @@
 
 
 ## IMPROVEMENTS:
-- systemd/journalctl: use a less shit pager
-  - there's an env var for it: SYSTEMD_PAGER? and a flag for journalctl
 - kernels: ship the same kernel on every machine
   - then i can tune the kernels for hardening, without duplicating that work 4 times
 - zfs: replace this with something which doesn't require a custom kernel build

hosts/common/programs/less.nix

@@ -4,5 +4,15 @@
     sandbox.method = "bwrap";
     sandbox.autodetectCliPaths = "existingFile";
     env.PAGER = "less";
+    # LESS flags:
+    # - F = quit if output fits on one screen
+    # - K = exit on ctrl+c
+    # - M = "long prompt"
+    # - R = output raw control characters
+    # - S = chop long lines instead of wrapping
+    # - X = Don't use termcap init/deinit strings (hence, `less` output is visible on the terminal even after exiting)
+    # SYSTEMD_LESS defaults to FRSXMK
+    env.LESS = "FRMK";
+    env.SYSTEMD_LESS = "FRMK";  #< used by journalctl
   };
 }