man: add example os-release mangling in python

This is also not entirely obvious. I think the code I came
up with is pretty elegant ;] The final part of of the code that makes
use of the parsed data is kept very similar to the shell code on purpose,
even though it could be written a bit more idiomatically.

1 files changed, 28 insertions, 0 deletions

diff --git a/man/check-os-release.py b/man/check-os-release.py
new file mode 100644
index 0000000000..f6d23c8c46
--- /dev/null
+++ b/man/check-os-release.py
@@ -0,0 +1,28 @@
+#!/usr/bin/python
+
+import ast
+import re
+
+def read_os_release():
+    try:
+        f = open('/etc/os-release')
+    except FileNotFoundError:
+        f = open('/usr/lib/os-release')
+
+    for line_number, line in enumerate(f):
+        if m := re.match(r'([A-Z][A-Z_0-9]+)=(.*)', line):
+            name, val = m.groups()
+            if val and val[0] in '"\'':
+                val = ast.literal_eval(val)
+            yield name, val
+        else:
+            print(f'Warning: bad line {line_number}: {line}', file=sys.stderr)
+
+os_release = dict(read_os_release())
+
+pretty_name = os_release.get('PRETTY_NAME', 'Linux')
+print(f'Running on {pretty_name}')
+
+if (os_release.get('ID', 'linux') == 'debian' or
+    os_release.get('ID_LIKE', None) == 'debian'):
+    print('Looks like Debian!')