tldr: env: Add TLDR_PLATFORM env var to override platform detection

Add support for the TLDR_PLATFORM environment variable to let users
specify the desired platform (e.g., "linux", "macos", "windows") for
fetching TLDR pages.
This overrides the default platform detection.
The --platform option remains supported for per-command overrides.

Signed-off-by: Itamar Shalev <[email protected]>

Author: Itamar Shalev

README.md

@@ -91,8 +91,22 @@ export TLDR_CACHE_MAX_AGE=720
 export TLDR_PAGES_SOURCE_LOCATION="https://raw.githubusercontent.com/tldr-pages/tldr/main/pages"
 export TLDR_DOWNLOAD_CACHE_LOCATION="https://github.com/tldr-pages/tldr/releases/latest/download/tldr.zip"
 export TLDR_OPTIONS=short
+export TLDR_PLATFORM=linux
 ```
 
+### Platform
+The platform that tldr will use is determined by the `TLDR_PLATFORM` environment variable.
+If it is not set, the client will try to determine the platform automatically based on the system it is running on.
+The following values are supported:
+- `linux`
+- `windows`
+- `android`
+- `freebsd`
+- `netbsd`
+- `openbsd`
+- `osx`
+- `sunos`
+
 ### Cache
 
 Cache is downloaded from `TLDR_DOWNLOAD_CACHE_LOCATION` (defaults to the one described in [the client specification](https://github.com/tldr-pages/tldr/blob/main/CLIENT-SPECIFICATION.md#caching)), unzipped and extracted into the [local cache directory](#cache-location). Pages are loaded directly from `TLDR_PAGES_SOURCE_LOCATION` if `tldr <command>` is used.

tldr.py

@@ -202,6 +202,13 @@ def update_page_for_platform(
 
 
 def get_platform() -> str:
+    if platform := os.environ.get('TLDR_PLATFORM'):
+        platform = platform.lower()
+        if platform in OS_DIRECTORIES:
+            return OS_DIRECTORIES[platform]
+        else:
+            print("Warning: Invalid platform specified in environment variable TLDR_PLATFORM.")
+
     for key in OS_DIRECTORIES:
         if sys.platform.startswith(key):
             return OS_DIRECTORIES[key]