Allow to skip update checks

README.md

@@ -135,6 +135,7 @@ This is the complete list of env variables that change GHCup behavior:
 * `GHCUP_INSTALL_BASE_PREFIX`: the base of ghcup (default: `$HOME`)
 * `GHCUP_CURL_OPTS`: additional options that can be passed to curl
 * `GHCUP_WGET_OPTS`: additional options that can be passed to wget
+* `GHCUP_SKIP_UPDATE_CHECK`: Skip the (possibly annoying) update check when you run a command
 * `CC`/`LD` etc.: full environment is passed to the build system when compiling GHC via GHCup
 
 ### Installing custom bindists

app/ghcup/Main.hs

@@ -1144,7 +1144,10 @@ Report bugs at <https://gitlab.haskell.org/haskell/ghcup-hs/issues>|]
 
           case optCommand of
             Upgrade _ _ -> pure ()
-            _ -> runLogger $ flip runReaderT appstate $ checkForUpdates
+            _ -> do
+              lookupEnv "GHCUP_SKIP_UPDATE_CHECK" >>= \case
+                Nothing -> runLogger $ flip runReaderT appstate $ checkForUpdates
+                Just _ -> pure ()
 
 
           -- ensure global tools