programs: less: enable color highlighting

hosts/common/programs/less.nix

@@ -2,16 +2,22 @@
 {
   sane.programs.less = {
     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)
+    # - --LINE-NUMBERS (N) = render EVERY line with its number in the left column
+    # - --LONG-PROMPT (M) = "long prompt"
+    # - --RAW-CONTROL-CHARS (R) = output raw control characters
+    # - --chop-long-lines (S) = chop long lines instead of wrapping
+    # - --incsearch = start searching immediately as you type `/<search-term>`
+    # - --no-init (X) = Don't use termcap init/deinit strings (hence, `less` output is visible on the terminal even after exiting)
+    # - --quit-if-one-screen (F) = quit if output fits on one screen
+    # - --quit-on-intr (K) = exit on ctrl+c
+    # - --shift=.n = left/right arrow-keys scroll by `n` screen widths
+    # - --use-color = enable color instead of just monochrome (highlights search matches)
     # SYSTEMD_LESS defaults to FRSXMK
-    env.LESS = "FRMK";
-    env.SYSTEMD_LESS = "FRMK";  #< used by journalctl
+    env = rec {
+      PAGER = "less";
+      LESS = "--incsearch --LONG-PROMPT --quit-if-one-screen --quit-on-intr --RAW-CONTROL-CHARS --shift=.2 --use-color";
+      SYSTEMD_LESS = LESS;  #< used by journalctl
+    };
   };
 }