Setting group permissions with python

Question

That is my setup:

I have a VirtualMachine (Ubuntu 14.04. LTS), where there is running a PostgreSQL/PostGIS database.

With Windows 7 in QGIS I connect to this database and load feature layer into my GIS project.

With some python code I create a file with a tile ID and some information.

import os
import io
import time

layer=None
for lyr in QgsMapLayerRegistry.instance().mapLayers().values():
if lyr.name() == "fishnet_final":
    layer = lyr

for f in layer.selectedFeatures():
    pth = os.path.join(os.path.dirname(r'H:\path_to_file\'), str(f['name']) + "_" + str(time.strftime("%Y-%m-%d")) + "_" + str(f['country']) + ".txt")
    fle = open(pth,'wb')    
    fle.writelines(str(f['name']))
    fle.write('\n')
    fle.write(str(time.strftime("%Y-%d-%m")))
    fle.write('\n')
    fle.write(str(f['country']))
    fle.write('\n')
    fle.close()
    os.rename(pth, pth.replace(' ', ''))

The file has the permissions:

-rwx------

I want to set also the same permissions for my group and other.

-rwxrwxrwx

I tried:

import shlex
command=shlex.split("chmod 777 r'H:\path_to_file\file.txt'") 
subprocess.call(command)

No success.

What was working is:

command=shlex.split("touch r'H:\path_to_file\file.txt'")

OR

command=shlex.split("rm r'H:\path_to_file\file.txt'")

Why doesn't work the chmod command?

Under UNIX I can chmod this file and I'am the same user like in Windows.

I also tried the os.chmod method. But no success.

import os, stat
st = os.stat(r'H:\path_to_file\file.txt')
os.chmod(r'H:\path_to_file\file.txt', st.st_mode | 0o111 )

UPDATE

When I do a "chmod 777 file" under UNIX (Solaris) the permissions are

-rwxrwxrwx

What I can do now is to downgrade/remove permissions under Windows in the GIS project:

subprocess.call(r'chmod 400 "H:\path_to_file\file.txt"', shell=True)
0
-r-xr-xr-x

With this command I get a 0 feedback in the python console output

I also get a 0 feedback when I do a chmod 777 on the new file but nothing happens.

The Problem is that I can only downgrade permissions. I can't set new permissions!

Answer 1

Try this (I don't have a Linux machine right now to test it):

import subprocess
subprocess.call(r'chmod 777 "H:\path_to_file\file.txt"', shell=True)

If the filename is user-supplied, you should avoid shell=True for security reasons. You may try:

filename = r"H:\path_to_file\file.txt"
subprocess.call(['chmod','777',filename])

Answer 2

What is the intention with the r character in your shell commands? Do you mean to put it in front of the entire string? Have you checked which file is generated by touch?

When I try your example, it runs this command: ['touch', 'rH:\\path_to_file\x0cile.txt'], that is creating the file rH:\path_to_file\file.txt

This works fine for me:

command=shlex.split("chmod 777 'H:\path_to_file\file.txt'") subprocess.call(command)