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authorZbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>2017-01-23 01:11:45 -0500
committerZbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>2017-02-20 18:49:14 -0500
commit1bd2d4e31b739586cf91ddfe65349f79298af013 (patch)
tree4314c63d1e788788ab1366c9c1b2586d91bf38d4 /man/90-rearrange-path.py
parent64691d2024d3bd202c85c52069f185afee2b8e43 (diff)
man: add systemd.environment-generator(7) with two examples
v2: - add example files to EXTRA_DIST v3: - rework for the new scheme where nothing is written to disk v4: - use separate dirs for system and user env generators
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diff --git a/man/90-rearrange-path.py b/man/90-rearrange-path.py
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+#!/usr/bin/python3
+
+"""
+
+Proof-of-concept systemd environment generator that makes sure that bin dirs
+are always after matching sbin dirs in the path.
+(Changes /sbin:/bin:/foo/bar to /bin:/sbin:/foo/bar.)
+
+This generator shows how to override the configuration possibly created by
+earlier generators. It would be easier to write in bash, but let's have it
+in Python just to prove that we can, and to serve as a template for more
+interesting generators.
+
+"""
+
+import os
+import pathlib
+
+def rearrange_bin_sbin(path):
+ """Make sure any pair of …/bin, …/sbin directories is in this order
+
+ >>> rearrange_bin_sbin('/bin:/sbin:/usr/sbin:/usr/bin')
+ '/bin:/sbin:/usr/bin:/usr/sbin'
+ """
+ items = [pathlib.Path(p) for p in path.split(':')]
+ for i in range(len(items)):
+ if 'sbin' in items[i].parts:
+ ind = items[i].parts.index('sbin')
+ bin = pathlib.Path(*items[i].parts[:ind], 'bin', *items[i].parts[ind+1:])
+ if bin in items[i+1:]:
+ j = i + 1 + items[i+1:].index(bin)
+ items[i], items[j] = items[j], items[i]
+ return ':'.join(p.as_posix() for p in items)
+
+if __name__ == '__main__':
+ path = os.environ['PATH'] # This should be always set.
+ # If it's not, we'll just crash, we is OK too.
+ new = rearrange_bin_sbin(path)
+ if new != path:
+ print('PATH={}'.format(new))