dlenski · September 26, 2025 19:38 · Sep 26, 2025 · Sep 26, 2025 · Sep 26, 2025 · Sep 26, 2025
diff --git a/winenv.py b/winenv.py
@@ -126,15 +126,14 @@ def _convert_paths(winenv: Mapping, paths: Union[Container, bool] = True) -> Map
 
     if args.associative:
         print(f'declare -A {args.associative}')
-        print('; '.join(f'{args.associative}[{shlex.quote(var)}]={shlex.quote(val)}'))
+        for var, val in winenv.items():
+            print(f'{args.associative}[{shlex.quote(var)}]={shlex.quote(val)}')
     elif args.format == 'json':
         json.dump(winenv, sys.stdout)
     else:
         kw = 'setenv' if args.format == 'csh' else 'export'
-        delim = ''
         for var, val in winenv.items():
             if not var.isidentifier():
                 warn(f'Windows environment variable {var!r} is not a valid POSIX shell identifier, skipping.')
             else:
-                print(f'{delim}{kw} {args.prefix}{var}={shlex.quote(val)}', end='')
-                delim='; '
+                print(f'{kw} {args.prefix}{var}={shlex.quote(val)}')
diff --git a/winenv.py b/winenv.py
@@ -23,7 +23,6 @@
 
 import subprocess as sp
 import json
-import os
 from typing import Union, Container, Mapping
 from pathlib import PureWindowsPath, PurePosixPath
 import shlex
@@ -35,7 +34,6 @@
 
 BACKSLASH = '\\'
 DOUBLE_BACKSLASH = '\\\\'
-DETECT_WSL_PATH = '/proc/sys/fs/binfmt_misc/WSLInterop'
 POWERSHELL_EXE = '/mnt/c/Windows/System32/WindowsPowerShell/v1.0/powershell.exe'
 
 
@@ -139,4 +137,4 @@ def _convert_paths(winenv: Mapping, paths: Union[Container, bool] = True) -> Map
                 warn(f'Windows environment variable {var!r} is not a valid POSIX shell identifier, skipping.')
             else:
                 print(f'{delim}{kw} {args.prefix}{var}={shlex.quote(val)}', end='')
-                delim='; '
+                delim='; '
diff --git a/winenv.py b/winenv.py
@@ -23,6 +23,7 @@
 
 import subprocess as sp
 import json
+import os
 from typing import Union, Container, Mapping
 from pathlib import PureWindowsPath, PurePosixPath
 import shlex
@@ -34,6 +35,7 @@
 
 BACKSLASH = '\\'
 DOUBLE_BACKSLASH = '\\\\'
+DETECT_WSL_PATH = '/proc/sys/fs/binfmt_misc/WSLInterop'
 POWERSHELL_EXE = '/mnt/c/Windows/System32/WindowsPowerShell/v1.0/powershell.exe'
 
 
@@ -126,13 +128,15 @@ def _convert_paths(winenv: Mapping, paths: Union[Container, bool] = True) -> Map
 
     if args.associative:
         print(f'declare -A {args.associative}')
-        for var, val in winenv.items():
-            print(f'{args.associative}[{shlex.quote(var)}]={shlex.quote(val)}')
+        print('; '.join(f'{args.associative}[{shlex.quote(var)}]={shlex.quote(val)}'))
     elif args.format == 'json':
         json.dump(winenv, sys.stdout)
     else:
         kw = 'setenv' if args.format == 'csh' else 'export'
+        delim = ''
         for var, val in winenv.items():
             if not var.isidentifier():
-                warn(f'Windows environment variable {var!r} is not a valid POSIX shell identifier, commenting out.')
-            print(("" if var.isidentifier() else "# ") + f'{kw} {args.prefix}{var}={shlex.quote(val)}')
+                warn(f'Windows environment variable {var!r} is not a valid POSIX shell identifier, skipping.')
+            else:
+                print(f'{delim}{kw} {args.prefix}{var}={shlex.quote(val)}', end='')
+                delim='; '
diff --git a/winenv.py b/winenv.py
@@ -23,7 +23,6 @@
 
 import subprocess as sp
 import json
-import os
 from typing import Union, Container, Mapping
 from pathlib import PureWindowsPath, PurePosixPath
 import shlex
@@ -35,7 +34,6 @@
 
 BACKSLASH = '\\'
 DOUBLE_BACKSLASH = '\\\\'
-DETECT_WSL_PATH = '/proc/sys/fs/binfmt_misc/WSLInterop'
 POWERSHELL_EXE = '/mnt/c/Windows/System32/WindowsPowerShell/v1.0/powershell.exe'
 
 

diff --git a/winenv.py b/winenv.py
@@ -23,6 +23,7 @@
 
 import subprocess as sp
 import json
+import os
 from typing import Union, Container, Mapping
 from pathlib import PureWindowsPath, PurePosixPath
 import shlex
@@ -34,14 +35,16 @@
 
 BACKSLASH = '\\'
 DOUBLE_BACKSLASH = '\\\\'
+DETECT_WSL_PATH = '/proc/sys/fs/binfmt_misc/WSLInterop'
+POWERSHELL_EXE = '/mnt/c/Windows/System32/WindowsPowerShell/v1.0/powershell.exe'
 
 
 def _load_winenv() -> dict:
     env2json = '[System.Environment]::GetEnvironmentVariables() | ConvertTo-Json'
     # Robustness fixes based on https://github.com/wslutilities/wslu/blob/1bb1b53c0532394a1433b2eaa041b1c1e6ce0b69/src/wslu-header#L290,
     # with the addition of ErrorActionPreference from https://stackoverflow.com/a/9949909/20789.
     cli = [
-        '/mnt/c/Windows/System32/WindowsPowerShell/v1.0/powershell.exe',
+        POWERSHELL_EXE,
         '-NoProfile', '-NonInteractive', '-ExecutionPolicy', 'Bypass', '-Command',
         '$ErrorActionPreference = "Stop"; [Console]::OutputEncoding = [System.Text.Encoding]::UTF8; ' + env2json
     ]

diff --git a/winenv.py b/winenv.py
@@ -4,7 +4,7 @@
 Access Windows environment variables from Python under WSL
 
 The :py:data:`winenv` and py:data:`winenv_wslpath` objects are
-immutable mappings, lazy-loaded upon initial usage.
+immutable mappings, loaded at module import time.
 
 py:data:`winenv` contains the unmodified Windows environment variables,
 while py:data:`winenv_wslpath` attempts to convert all ``PATH``-like

diff --git a/winenv.py b/winenv.py
@@ -1,3 +1,5 @@
+#!/usr/bin/env python3
+
 r'''
 Access Windows environment variables from Python under WSL
 
@@ -25,10 +27,14 @@
 from pathlib import PureWindowsPath, PurePosixPath
 import shlex
 import sys
+
 from warnings import warn
 
 __all__ = ['winenv', 'winenv_wslpath']
 
+BACKSLASH = '\\'
+DOUBLE_BACKSLASH = '\\\\'
+
 
 def _load_winenv() -> dict:
     env2json = '[System.Environment]::GetEnvironmentVariables() | ConvertTo-Json'
@@ -52,21 +58,21 @@ def _convert_paths(winenv: Mapping, paths: Union[Container, bool] = True) -> Map
         return winenv
     j = {}
     for var, vals in winenv.items():
-        convert = vals.startswith('\\') or vals[1:2] == ':' if paths == True else var in paths           
+        convert = vals.startswith(BACKSLASH) or (vals[0:1].isalpha() and vals[1:2] == ':') if paths == True else var in paths           
         if convert:
             winvals = map(PureWindowsPath, vals.split(';'))
             outvals = []
             for val in winvals:
-                if val.anchor.startswith('\\\\'):
+                if val.anchor.startswith(DOUBLE_BACKSLASH):
                     warn(f'Windows environment variable {var!r} contains UNC path {shlex.quote(str(val))}, not converting')
-                elif val.anchor == '\\':
+                elif val.anchor == BACKSLASH:
                     anchor = winenv.get('SystemDrive', 'C:')
                     warn(f'Windows environment variable {var!r} contains driveless path {shlex.quote(str(val))}, assuming {anchor!r}')
-                    val = PurePosixPath(f'/mnt/{anchor.rstrip("\\").removesuffix(":").lower()}') / val.relative_to(val.anchor)
+                    val = PurePosixPath(f'/mnt/{anchor.rstrip(BACKSLASH).removesuffix(":").lower()}') / val.relative_to(val.anchor)
                 elif not val.is_absolute():
                     warn(f'Windows environment variable {var!r} contains relative path {shlex.quote(str(val))}, not converting')
                 else:                        
-                    val = PurePosixPath(f'/mnt/{val.anchor.rstrip("\\").removesuffix(":").lower()}') / val.relative_to(val.anchor)
+                    val = PurePosixPath(f'/mnt/{val.anchor.rstrip(BACKSLASH).removesuffix(":").lower()}') / val.relative_to(val.anchor)
                 outvals.append(str(val))
             else:
                 j[var] = ':'.join(outvals)
@@ -81,6 +87,11 @@ def _convert_paths(winenv: Mapping, paths: Union[Container, bool] = True) -> Map
     winenv_wslpath = MappingProxyType(_convert_paths(winenv))
 
 else:
+    # Monkey-patch reduced warning verbosity (see https://stackoverflow.com/a/2187390)
+    import warnings
+    _fw = warnings.formatwarning
+    warnings.formatwarning = lambda *args, **kwargs: _fw(*args, **kwargs).splitlines(keepends=True)[0]
+
     import argparse
     p = argparse.ArgumentParser(
         description='''Capture Windows environment variables in a format that can be used under Windows Subsystem for Linux.

diff --git a/winenv.py b/winenv.py
@@ -0,0 +1,126 @@
+r'''
+Access Windows environment variables from Python under WSL
+
+The :py:data:`winenv` and py:data:`winenv_wslpath` objects are
+immutable mappings, lazy-loaded upon initial usage.
+
+py:data:`winenv` contains the unmodified Windows environment variables,
+while py:data:`winenv_wslpath` attempts to convert all ``PATH``-like
+variables to WSL paths.
+
+Example:
+
+   from wslenv import winenv, winenv_wslpath
+   print("Windows username is", winenv['USERNAME'])
+   print("WSL-ified Windows PATH is", winenv_wslpath['PATH'])
+
+This requires WSL and PowerShell 3.0 installed in the standard location of
+``C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe``.
+It grew out of https://stackoverflow.com/a/79662726
+'''
+
+import subprocess as sp
+import json
+from typing import Union, Container, Mapping
+from pathlib import PureWindowsPath, PurePosixPath
+import shlex
+import sys
+from warnings import warn
+
+__all__ = ['winenv', 'winenv_wslpath']
+
+
+def _load_winenv() -> dict:
+    env2json = '[System.Environment]::GetEnvironmentVariables() | ConvertTo-Json'
+    # Robustness fixes based on https://github.com/wslutilities/wslu/blob/1bb1b53c0532394a1433b2eaa041b1c1e6ce0b69/src/wslu-header#L290,
+    # with the addition of ErrorActionPreference from https://stackoverflow.com/a/9949909/20789.
+    cli = [
+        '/mnt/c/Windows/System32/WindowsPowerShell/v1.0/powershell.exe',
+        '-NoProfile', '-NonInteractive', '-ExecutionPolicy', 'Bypass', '-Command',
+        '$ErrorActionPreference = "Stop"; [Console]::OutputEncoding = [System.Text.Encoding]::UTF8; ' + env2json
+    ]
+    try:
+        return json.loads(sp.check_output(cli, stdin=sp.DEVNULL))
+    except sp.CalledProcessError as exc:
+        raise NotImplementedError("Could not get environment variables from PowerShell in JSON format; PowerShell 3.0+ is required") from exc
+    except FileNotFoundError as exc:
+        raise NotImplementedError(f"Could not invoke {cli[0]}; may not be running under WSL") from exc
+
+
+def _convert_paths(winenv: Mapping, paths: Union[Container, bool] = True) -> Mapping:
+    if not paths:
+        return winenv
+    j = {}
+    for var, vals in winenv.items():
+        convert = vals.startswith('\\') or vals[1:2] == ':' if paths == True else var in paths           
+        if convert:
+            winvals = map(PureWindowsPath, vals.split(';'))
+            outvals = []
+            for val in winvals:
+                if val.anchor.startswith('\\\\'):
+                    warn(f'Windows environment variable {var!r} contains UNC path {shlex.quote(str(val))}, not converting')
+                elif val.anchor == '\\':
+                    anchor = winenv.get('SystemDrive', 'C:')
+                    warn(f'Windows environment variable {var!r} contains driveless path {shlex.quote(str(val))}, assuming {anchor!r}')
+                    val = PurePosixPath(f'/mnt/{anchor.rstrip("\\").removesuffix(":").lower()}') / val.relative_to(val.anchor)
+                elif not val.is_absolute():
+                    warn(f'Windows environment variable {var!r} contains relative path {shlex.quote(str(val))}, not converting')
+                else:                        
+                    val = PurePosixPath(f'/mnt/{val.anchor.rstrip("\\").removesuffix(":").lower()}') / val.relative_to(val.anchor)
+                outvals.append(str(val))
+            else:
+                j[var] = ':'.join(outvals)
+        else:
+            j[var] = vals
+    return j
+
+
+if __name__ != '__main__':    
+    from types import MappingProxyType
+    winenv = MappingProxyType(_load_winenv())
+    winenv_wslpath = MappingProxyType(_convert_paths(winenv))
+
+else:
+    import argparse
+    p = argparse.ArgumentParser(
+        description='''Capture Windows environment variables in a format that can be used under Windows Subsystem for Linux.
+        Requires PowerShell 3.0+ (Windows 8+).
+        Under bash or other POSIX Bourne shells, use: eval "$(%(prog)s)"''')
+    g = p.add_argument_group('Path conversion')
+    x = g.add_mutually_exclusive_group()
+    x.add_argument('-w', '--wslpath', metavar='COMMA_SEPARATED_LIST', default=True,
+                   help="Only try to convert these specific Windows environment variables to WSL paths (default is to try to convert all)")
+    x.add_argument('-W', '--no-wslpath', dest='wslpath', action='store_false',
+                   help='Do not try to convert any Windows environment variables containing paths to WSL paths (default is to try to convert all)')    
+    g = p.add_argument_group('Output format')
+    x = g.add_mutually_exclusive_group()
+    x.add_argument('-A', '--associative', metavar='ARRAY_NAME',
+                   help='Output environment variables in named associative array (Bash extension)')
+    x.add_argument('-b', '--sh', '--bash', dest='format', action='store_const', const='sh', default='sh',
+                   help='Output environment variables as POSIX Bourne shell "export" commands (the default)')
+    x.add_argument('-c', '--csh', dest='format', action='store_const', const='csh',
+                   help='Output environment variables as C Shell "setenv" commands')
+    x.add_argument('-j', '--json', dest='format', action='store_const', const='json',
+                   help='Output environment variables as JSON')
+    p.add_argument('-p', '--prefix', default='WIN_', help='Prefix for variable names in sh/csh output (default %(default)r)')
+    args = p.parse_args()
+
+    try:
+        winenv = _load_winenv()
+    except Exception as exc:
+        p.error(f'Error loading Windows environment variables: {exc.args}')
+
+    winenv = _convert_paths(winenv, paths=args.wslpath)
+
+    if args.associative:
+        print(f'declare -A {args.associative}')
+        for var, val in winenv.items():
+            print(f'{args.associative}[{shlex.quote(var)}]={shlex.quote(val)}')
+    elif args.format == 'json':
+        json.dump(winenv, sys.stdout)
+    else:
+        kw = 'setenv' if args.format == 'csh' else 'export'
+        for var, val in winenv.items():
+            if not var.isidentifier():
+                warn(f'Windows environment variable {var!r} is not a valid POSIX shell identifier, commenting out.')
+            print(("" if var.isidentifier() else "# ") + f'{kw} {args.prefix}{var}={shlex.quote(val)}')