cleanup gnuplot command

README.md

@@ -51,6 +51,15 @@ Based loosely off sc-im (spreadsheet calculator improvised), which has dumb keyb
 | `:q` | Quit program |
 | `:q!` | Quit program, even if the file isn't saved |
 
+#### Visual mode commands
+
+These commands operate on selections.
+
+| Commmand | Description |
+| - | - |
+| `:plot` | Plots the current selection to `plog.png` using gnuplot |
+| `:export <filename>` | Exports the current selection to a new file |
+
 ## Math / Functions
 
 ### Math

src/app/mode.rs

@@ -216,10 +216,16 @@ impl Mode {
                     let s = s.replace("$OUTPUT", "/tmp/output.png");
                     let _ = fs::write("/tmp/plot.p", s);
 
-                    let _ = Command::new("gnuplot").arg("/tmp/plot.p").output();
-                    let _ = fs::copy("/tmp/output.png", output_filename);
-
-                    app.msg = StatusMessage::info("Wrote gnuplot data to /tmp");
+                    let cmd_res= Command::new("gnuplot").arg("/tmp/plot.p").output();
+                    if let Err(err) = cmd_res {
+                        match err.kind() {
+                            std::io::ErrorKind::NotFound => app.msg = StatusMessage::error("Error - Is gnuplot installed?"),
+                            _ => app.msg = StatusMessage::error(format!("{err}")),
+                        };
+                    } else {
+                        let _ = fs::copy("/tmp/output.png", output_filename);
+                        app.msg = StatusMessage::info(format!("Created {output_filename}. Artifacts are in /tmp"));
+                    }
                     app.mode = Mode::Normal
                 }
                 _ => {}