Merge pull request #12 from PRESFIL/support-STACK_ROOT-env

Support `$STACK_ROOT` environment variable

ChangeLog.md

@@ -1,5 +1,9 @@
 # Release history for stack-clean-old
 
+## Unreleased
+- add support for `${STACK_ROOT}` environment variable to override the Stack
+  Root location
+
 ## 0.4.7 (2023-08-22)
 - add --tarballs for programs/ ghc tarballs too (#9)
 - bug fix to match both ghc-*.* and ghc-variant-*.* (#14)

README.md

@@ -6,13 +6,17 @@ snapshot builds and ghc versions to recover diskspace.
 ## Usage
 `stack-clean-old [size|list|remove|keep-minor|purge-older|delete-work] [(-P|--project)|(-G|--global)|(-C|--compilers)|(-T|--tarballs)] [(-s|--subdirs)|(-r|--recursive)] [-d|--delete] [GHCVER]`
 
-In a project directory it acts on `.stack-work/install/` by default,
-otherwise on `~/.stack/{snapshots,programs}/`.
+In a project directory it acts on `.stack-work/install/` by default, otherwise
+on the *Stack Root location* `${STACK_ROOT}/{snapshots,programs}/`. If
+`${STACK_ROOT}` is unset, the *Stack Root location* is `~/.stack/`. See
+[official documentation][stack_root].
+
+[stack_root]: https://docs.haskellstack.org/en/stable/environment_variables/#stack_root
 
 Subcommands:
 
 `size`:
-    prints the total size of `.stack-work/` or `~/.stack/`
+    prints the total size of `.stack-work/` of project(s) or the *Stack Root location*.
     (`size` does not take a GHCVER argument).
 
 `list`:

src/Directories.hs

@@ -9,17 +9,26 @@ where
 import Data.List.Extra
 import SimpleCmd (error')
 import System.Directory
+import System.Environment
 import System.FilePath
 import System.FilePath.Glob
 
 globDirs :: String -> IO [FilePath]
 globDirs pat = do
   map (dropPrefix "./") <$> namesMatching (pat ++ "/")
 
+getStackRootDir :: IO FilePath
+getStackRootDir = do
+  home <- getHomeDirectory
+  env <- lookupEnv "STACK_ROOT"
+  case env of
+    Just path | isAbsolute path -> return path
+    _                           -> return $ home </> ".stack"
+
 getStackSubdir :: FilePath -> IO FilePath
 getStackSubdir subdir = do
-  home <- getHomeDirectory
-  return $ home </> ".stack" </> subdir
+  stackRoot <- getStackRootDir
+  return $ stackRoot </> subdir
 
 switchToSystemDirUnder :: Maybe String -> FilePath -> IO ()
 switchToSystemDirUnder msystem dir = do