Develop Reference

Denied persmission to .py file on ev3dev, PuTTY

I have EV3 Lego Mindstorms and I instaled on it ev3dev operating system. I set the connection with the PC via SSH and using PuTTY I started to "programming". I used the cat > test2.py and wrote this code:
#!/usr/bin/env python3
import ev3dev.ev3 as ev3
motor = ev3.LargeMotor('outA')
motor.run_timed(time_sp = 1000, speed_sp = 500)
I saved the file and initialized it using ./test2.py. I got this output:
-bash: ./test2.py: Persmission denied
What caused it and what should I change?

try this:
sudo python3 test2.py
that will allows you to open almost anything in linux

Use ls -la ./test2.py in order to see the file permissions.
Look at the beginning of the output, you'll see something like this:
-rw-rw-r--
The first - means if is a directory or a file. In this case means that is a file.
Now If you observe the remaining chars there are 3 sets of 3 chars with means the permissions for the owner of the file, the owner group and the last set is for the rest of the users.
We have permissions to read, write and execute and in the example I showed there are read and write permissions for the owner user and the owner group but non permissions for the other users.
As Is said above you can just use sudo every time you execute the script but to run it with root privileges. However I would recommend you change your file permissions and using chmod
sudo chmod +x ./test2.py
This will let you execute the script. Take a look at chmod documentation to learn more: https://help.ubuntu.com/community/FilePermissions

Chmod in Python - [Errno 1] Operation not permitted

I'm trying to modify an application in my /Applications folder on OS X. I need to get read and write permissions, so I currently have:
os.chmod(appDir, 0644)
where appDir is the directory of my app. However, whenever I run the program, I get the error:
OSError: [Errno 1] Operation not permitted: '/Applications/Simplenote.app'
I would try sudo, but how would you enter the password through Python? (this is a Python script by the way)
Any help is appreciated.

If you are trying to run the script from a web site, change the target folders/files to be owned by the web user, e.g. www-data. sudo chown www-data * -R That fixed it for me.

Python CGI script permission denied when writing file

I've got a python script named test.cgi in /Library/WebServer/CGI-Executables. I have an index.html file in /Library/WebServer/Documents. My html file contains a form that posts to the CGI script and that works fine. When my script attempts to write a file I get the following error:
It doesn't matter what I specify as the output dir, I get the same error message. I've tried changing the permissions on the cgi-bin folder and the script but that doesn't work either. Any suggestions?

On Linux, a web server normally runs as an unprivileged user and group. Often user=www-data and group=www-data, but it depends on your setup. The CGI inherits this user and group.
To create a file as www-data you need to ensure the directory is writable to that user.
One common way is to make sure that the directory is in group www-data and writable. The following commands are an example:
$ chgrp www-data /Users/user/Documents/pictures
$ chmod g+rwx /Users/user/Documents/pictures
This will only work if you are yourself in group www-data (or root).
You might want to make existing files in that directory writable:
$ chgrp www-data /Users/user/Documents/pictures/*
$ chmod g+rw /Users/user/Documents/pictures/*
You also need to check that all the directories above /Users/user/Documents/pictures are accessible to www-data. So chgrp/chmod them as well if they are not open to anyone.

Looks like you don't have the write permissions at some point along the way to /Users/user/Documents/pictures/lol.jpg - you should modify permissions in there accordingly (whilst bearing in mind security implications)

OSError - Errno 13 Permission denied

I am trying to upload image through admin page, but it keeps saying:
[Errno 13] Permission denied: '/path/to/my/site/media/userfolder/2014/05/26'
the folders userfolder/2014/05/26 are created dynamically while uploading.
In Traceback, i found that the error is occuring during this command:
In /usr/lib64/python2.6/os.py Line 157. while calling
mkdir(name, mode)
meaning, it cannot create any folder as it doesnot have the permission to do this
I have OpenSuse as OS in Server. In httpd.conf, i have this:
<Directory /path/to/my/site/media>
Order allow,deny
Allow from all
</Directory>
Do I have to chmod or chown something?

You need to change the directory permission so that web server process can change the directory.
To change ownership of the directory, use chown:
chown -R user-id:group-id /path/to/the/directory
To see which user own the web server process (change httpd accordingly):
ps aux | grep httpd | grep -v grep
OR
ps -efl | grep httpd | grep -v grep

This may also happen if you have a slash before the folder name:
path = '/folder1/folder2'
OSError: [Errno 13] Permission denied: '/folder1'
comes up with an error but this one works fine:
path = 'folder1/folder2'

Probably you are facing problem when a download request is made by the maybe_download function call in base.py file.
There is a conflict in the permissions of the temporary files and I myself couldn't work out a way to change the permissions, but was able to work around the problem.
Do the following...
Download the four .gz files of the MNIST data set from the link ( http://yann.lecun.com/exdb/mnist/ )
Then make a folder names MNIST_data (or your choice in your working directory/ site packages folder in the tensorflow\examples folder).
Directly copy paste the files into the folder.
Copy the address of the folder (it probably will be
( C:\Python\Python35\Lib\site-packages\tensorflow\examples\tutorials\mnist\MNIST_data ))
Change the "\" to "/" as "\" is used for escape characters, to access the folder locations.
Lastly, if you are following the tutorials, your call function would be ( mnist = input_data.read_data_sets("MNIST_data/", one_hot=True) ) ;
change the "MNIST_data/" parameter to your folder location. As in my case would be ( mnist = input_data.read_data_sets("C:/Python/Python35/Lib/site-packages/tensorflow/examples/tutorials/mnist/MNIST_data", one_hot=True) )
Then it's all done.
Hope it works for you.

Another option is to ensure the file is not open anywhere else on your machine.

supplementing #falsetru's answer : run id in the terminal to get your user_id and group_id
Go the directory/partition where you are facing the challenge.
Open terminal, type id then press enter.
This will show you your user_id and group_id
then type
chown -R user-id:group-id .
Replace user-id and group-id
. at the end indicates current partition / repository
// chown -R 1001:1001 . (that was my case)

Simply try:
sudo cp /source /destination

Just close the file in case it is opened in the background. The error disappears by itself

The solution that worked out for me here when I was using python 3 os package for performing operations on a directory where I didn't have sufficient permissions and access to got resolved by running the python file with sudo (root) i.e.:
sudo python python_file_name.py
Any other utility that you might also plan on using to chmod or chown that directory would also only work when you run it with sudo.
# file_name.py
base_path = "./parent_dir/child_dir/"
user = os.stat(base_path).st_uid # for getting details of the current user owner of the dir
group = os.stat(base_path).st_gid # for getting details of the current group owner of the dir
print("Present owner and group of the specified path")
print("Owner:", user)
print("Group:", group)
os.chown(base_path, user, group) # change directory permissions
print("\nOwner id of the file:", os.stat(base_path).st_uid)
print("Group id of the file:", os.stat(base_path).st_gid)
os.mkdir(base_path+file_name,mode=0o666)
run the above file with sudo.
sudo python file_name.py
Hope this answer works out for you.
Forever indebted to stackoverflow and the dev community. All hail the devs.

How to run long Python script without re-prompt for credentials

I have a Python script, let's say install.py (which I am running as sudo), on OS X that installs homebrew, Xcode, pip, ruby, swig, and, ultimately, salt. The problem is that running and installing everything (Xcode CLI in partituclar) takes so long to run, that sudo times out, requiring another prompt for admin credentials.
Here's the thing. As part of install.py, before kicking off all the installations, I first create a local admin user by opening a subprocess and use:
make_admin_account = {
"mkdir -p /Users/%(accountname)s",
"sudo dscl . -create /Users/%(accountname)s",
"sudo dscl . -create /Users/%(accountname)s UserShell /bin/bash",
"sudo dscl . -create /Users/%(accountname)s RealName \"%(fullname)s\"",
"sudo dscl . -create /Users/%(accountname)s UniqueID \"%(uid)s\"",
"sudo dscl . -create /Users/%(accountname)s PrimaryGroupID 80",
"sudo dscl . -create /Users/%(accountname)s NFSHomeDirectory /Users/%(accountname)s",
"sudo dscl . -passwd /Users/%(accountname)s \"%(password)s\"",
"sudo dscl . -append /Groups/admin GroupMembership%(accountname)s",
"sudo dscl . -append /Groups/_appserveradm GroupMembership %(accountname)s",
"sudo dscl . -append /Groups/_appserverusr GroupMembership %(accountname)s",
"sudo chown -R %(accountname)s /Users/%(accountname)s",
"sudo createhomedir -c -u %(accountname)s"
}
So, now we have a local admin account. Pretty simply now, run through each of the installers. Let's jump ahead to where Xcode CLI had been installed, now we're kicking off homebrew:
print("Install Homebrew")
execute("sudo -H -u %s ruby homebrew_ruby" % accountname)
(execute() is just a simple function that's calling subprocess.Popen()) As soon as it encounters sudo, it wants admin credentials again. This is not desired behavior. So, how about passing a preexec_fn to the subprocess and running as the newly created admin account?
def demote(user_uid, user_gid):
def result():
os.setgid(user_gid)
os.getuid(user_uid)
return result
preexec_fn = demote(pwd.getpwnam(accountname).pw_uid, pwd.getpwnam(accountname).pw_gid)
execute("ruby homebrew_ruby", preexec_fn=preexec_fn)
Again, execute is just taking the preexec_fn argument and passing it to subprocess.Popen. What's returned is:
shell-init: error retrieving current directory: getcwd: cannot access parent directories: Permission denied
shell-init: error retrieving current directory: getcwd: cannot access parent directories: Permission denied
chdir: error retrieving current directory: getcwd: cannot access parent directories: Permission denied
chdir: error retrieving current directory: getcwd: cannot access parent directories: Permission denied
job-working-directory: error retrieving current directory: getcwd: cannot access parent directories: Permission denied
At this point, I'm thinking my new admin account is setup incorrectly. Exit script, and try su'ing to the new admin account I had just created:
shell-init: error retrieving current directory: getcwd: cannot access parent directories: Permission denied
Looks familiar.
So, to put my desire into a sentence: I'm looking for a way to keep a long Python script from prompting for admin creds after it times out in the default 5 minutes. I know that I could just edit /etc/sudoers:
Defaults timestamp_timeout=15
That ought to fix it...but I feel like there should be a better solution here that either I'm not seeing or haven't yet explored. If we could run it as a python child process with prexec_fn, that would be ideal.

In Python, check your os.getcwd(), you're probably running from a funky place.
Try passing cwd='/tmp' to process.Popen(). Everyone has permissions to /tmp!