File lives on windows vs linux in Python 3.4 - python

I have a script that I need to run on ubuntu and windows each using Python 3.4 and when I run on windows I get an exception, "PermissionError: [WinError 32] The process cannot access the file because it is being used by another process: 'C:\Users\me\Desktop\tmp9uvk57b4.txt'" while on linux, it works error free.
I've boiled down my problem to this example snippet. I'm not sure where the problem lies, but the snippet takes some text and writes it to a temporary file. After a while, it removes the temp file and that is where the error comes in.
#!/usr/bin/env python3
import os
import tempfile
msg = "THIS IS A HORRIBLE MESSAGE"
txt = None
try:
txt = tempfile.mkstemp(dir='.', suffix='.txt')[1]
with open(txt, "w") as f:
f.write(msg)
except Exception as exp:
raise exp
finally:
if txt:
os.remove(txt)
I assume there is some issue where windows doesn't close the file while linux does. Can I just explicitly close it again? Will that mess up anything on linux? Is there a good windows/linux gotcha resource?

tempfile.mkstemp has two return values, an open filehandle and the filename. You don't use the open filehandle, such that it is never closed. Therefore the error message.
import os
import tempfile
msg = "THIS IS A HORRIBLE MESSAGE"
fd, filename = tempfile.mkstemp(dir='.', suffix='.txt')
try:
with os.fdopen(fd, "w") as f:
f.write(msg)
finally:
os.remove(filename)

Related

How to close zip file, from zipfile?

When I try to unzip a file, and delete the old file, it says that it's still running, so I used the close function, but it doesn't close it.
Here is my code:
import zipfile
import os
onlineLatest = "testFile"
myzip = zipfile.ZipFile(f'{onlineLatest}.zip', 'r')
myzip.extractall(f'{onlineLatest}')
myzip.close()
os.remove(f"{onlineLatest}.zip")
And I get this error:
PermissionError: [WinError 32] The process cannot access the file because it is being used by another process: 'Version 0.1.2.zip'
Anyone know how to fix this?
Only other part that runs it before, but don't think it's the problem:
request = service.files().get_media(fileId=onlineVersionID)
fh = io.FileIO(f'{onlineLatest}.zip', mode='wb')
downloader = MediaIoBaseDownload(fh, request)
done = False
while done is False:
status, done = downloader.next_chunk()
print("Download %d%%." % int(status.progress() * 100))
myzip = zipfile.ZipFile(f'{onlineLatest}.zip', 'r')
myzip.extractall(f'{onlineLatest}')
myzip.close()
os.remove(f"{onlineLatest}.zip")
Try using with. That way you don't have to close at all. :)
with ZipFile(f'{onlineLatest}.zip', 'r') as zf:
zf.extractall(f'{onlineLatest}')
Wrapping up the discussion in the comments into an answer:
On the Windows operating system, unlike in Linux, a file cannot be deleted if there is any process on the system with a file handle open on that file.
In this case, you write the file via handle fh and read it back via myzip. Before you can delete it, you have to close both file handles.

Close already open csv in Python

Is there a way for Python to close that the file is already open file.
Or at the very least display a popup that file is open or a custom written error message popup for permission error.
As to avoid:
PermissionError: [Errno 13] Permission denied: 'C:\\zf.csv'
I've seen a lot of solutions that open a file then close it through python. But in my case. Lets say I left my csv open and then tried to run the job.
How can I make it so it closes the currently opened csv?
I've tried the below variations but none seem to work as they expect that I have already opened the csv at an earlier point through python. I suspect I'm over complicating this.
f = 'C:\\zf.csv'
file.close()
AttributeError: 'str' object has no attribute 'close'
This gives an error as there is no reference to opening of file but simply strings.
Or even..
theFile = open(f)
file_content = theFile.read()
# do whatever you need to do
theFile.close()
As well as:
fileobj=open('C:\\zf.csv',"wb+")
if not fileobj.closed:
print("file is already opened")
How do I close an already open csv?
The only workaround I can think of would be to add a messagebox, though I can't seem to get it to detect the file.
filename = "C:\\zf.csv"
if not os.access(filename, os.W_OK):
print("Write access not permitted on %s" % filename)
messagebox.showinfo("Title", "Close your CSV")
Try using a with context, which will manage the close (__exit__) operation smoothly at the end of the context:
with open(...) as theFile:
file_content = theFile.read()
You can also try to copy the file to a temporary file, and open/close/remove it at will. It requires that you have read access to the original, though.
In this example I have a file "test.txt" that is write-only (chmod 444) and it throws a "Permission denied" error if I try writing to it directly. I copy it to a temporary file that has "777" rights so that I can do what I want with it:
import tempfile, shutil, os
def create_temporary_copy(path):
temp_dir = tempfile.gettempdir()
temp_path = os.path.join(temp_dir, 'temp_file_name')
os.chmod(temp_path, 0o777); # give full access to the tempfile so we can copy
shutil.copy2(path, temp_path) # copy the original into the temp one
os.chmod(temp_path, 0o777); # replace permissions from the original file
return temp_path
path = "./test.txt" # original file
copy_path = create_temporary_copy(path) # temp copy
with open(copy_path, "w") as g: # can do what I want with it
g.write("TEST\n")
f = open("C:/Users/amol/Downloads/result.csv", "r")
print(f.readlines()) #just to check file is open
f.close()
# here you can add above print statement to check if file is closed or not. I am using python 3.5

exception stop read files python

I'm trying to control exceptions when reading files, but I have a problem. I'm new to Python, and I am not yet able to control how I can catch an exception and still continue reading text from the files I am accessing. This is my code:
import errno
import sys
class Read:
#FIXME do immutables this 2 const
ROUTE = "d:\Profiles\user\Desktop\\"
EXT = ".txt"
def setFileReaded(self, fileToRead):
content = ""
try:
infile = open(self.ROUTE+fileToRead+self.EXT)
except FileNotFoundError as error:
if error.errno == errno.ENOENT:
print ("File not found, please check the name and try again")
else:
raise
sys.exit()
with infile:
content = infile.read()
infile.close()
return content
And from another class I tell it:
read = Read()
print(read.setFileReaded("verbs"))
print(read.setFileReaded("object"))
print(read.setFileReaded("sites"))
print(read.setFileReaded("texts"))
Buy only print this one:
turn on
connect
plug
File not found, please check the name and try again
And no continue with the next files. How can the program still reading all files?
It's a little difficult to understand exactly what you're asking here, but I'll try and provide some pointers.
sys.exit() will terminate the Python script gracefully. In your code, this is called when the FileNotFoundError exception is caught. Nothing further will be ran after this, because your script will terminate. So none of the other files will be read.
Another thing to point out is that you close the file after reading it, which is not needed when you open it like this:
with open('myfile.txt') as f:
content = f.read()
The file will be closed automatically after the with block.

check if a file is open in Python

In my app, I write to an excel file. After writing, the user is able to view the file by opening it. But if the user forgets to close the file before any further writing, a warning message should appear. So I need a way to check this file is open before the writing process. Could you supply me with some python code to do this task?
If all you care about is the current process, an easy way is to use the file object attribute "closed"
f = open('file.py')
if f.closed:
print 'file is closed'
This will not detect if the file is open by other processes!
source: http://docs.python.org/2.4/lib/bltin-file-objects.html
I assume that you're writing to the file, then closing it (so the user can open it in Excel), and then, before re-opening it for append/write operations, you want to check that the file isn't still open in Excel?
This is how you could do that:
while True: # repeat until the try statement succeeds
try:
myfile = open("myfile.csv", "r+") # or "a+", whatever you need
break # exit the loop
except IOError:
input("Could not open file! Please close Excel. Press Enter to retry.")
# restart the loop
with myfile:
do_stuff()
For windows only
None of the other provided examples would work for me when dealing with this specific issue with excel on windows 10. The only other option I could think of was to try and rename the file or directory containing the file temporarily, then rename it back.
import os
try:
os.rename('file.xls', 'tempfile.xls')
os.rename('tempfile.xls', 'file.xls')
except OSError:
print('File is still open.')
You could use with open("path") as file: so that it automatically closes, else if it's open in another process you can maybe try
as in Tims example you should use except IOError to not ignore any other problem with your code :)
try:
with open("path", "r") as file: # or just open
# Code here
except IOError:
# raise error or print
Using
try:
with open("path", "r") as file:#or just open
may cause some troubles when file is opened by some other processes (i.e. user opened it manually).
You can solve your poblem using win32com library.
Below code checks if any excel files are opened and if none of them matches the name of your particular one, openes a new one.
import win32com.client as win32
xl = win32.gencache.EnsureDispatch('Excel.Application')
my_workbook = "wb_name.xls"
xlPath="my_wb_path//" + my_workbook
if xl.Workbooks.Count > 0:
# if none of opened workbooks matches the name, openes my_workbook
if not any(i.Name == my_workbook for i in xl.Workbooks):
xl.Workbooks.Open(Filename=xlPath)
xl.Visible = True
#no workbooks found, opening
else:
xl.Workbooks.Open(Filename=xlPath)
xl.Visible = True
'xl.Visible = True is not necessary, used just for convenience'
Hope this will help
Try this method if the above methods corrupt your excel file.
This function attempts to rename the file with its own name. If the file has already been opened, the edit will be reject by the os and an OSError exception will be raised. It does not touch the inner code so it will not corrupt your excel files. LMK if it worked for you.
def check_file_status(self):
try:
os.rename("file1.xlsx", "file1.xlsx")
print("File is closed.")
except OSError:
print("File is opened.")
if myfile.closed == False:
print("File is still open ################")
Just use this function. It will close any already opened excel file
import os
def close():
try:
os.system('TASKKILL /F /IM excel.exe')
except Exception:
print("KU")
close()

Create a temporary FIFO (named pipe) in Python?

How can you create a temporary FIFO (named pipe) in Python? This should work:
import tempfile
temp_file_name = mktemp()
os.mkfifo(temp_file_name)
open(temp_file_name, os.O_WRONLY)
# ... some process, somewhere, will read it ...
However, I'm hesitant because of the big warning in Python Docs 11.6 and potential removal because it's deprecated.
EDIT: It's noteworthy that I've tried tempfile.NamedTemporaryFile (and by extension tempfile.mkstemp), but os.mkfifo throws:
OSError -17: File already exists
when you run it on the files that mkstemp/NamedTemporaryFile have created.
os.mkfifo() will fail with exception OSError: [Errno 17] File exists if the file already exists, so there is no security issue here. The security issue with using tempfile.mktemp() is the race condition where it is possible for an attacker to create a file with the same name before you open it yourself, but since os.mkfifo() fails if the file already exists this is not a problem.
However, since mktemp() is deprecated you shouldn't use it. You can use tempfile.mkdtemp() instead:
import os, tempfile
tmpdir = tempfile.mkdtemp()
filename = os.path.join(tmpdir, 'myfifo')
print filename
try:
os.mkfifo(filename)
except OSError, e:
print "Failed to create FIFO: %s" % e
else:
fifo = open(filename, 'w')
# write stuff to fifo
print >> fifo, "hello"
fifo.close()
os.remove(filename)
os.rmdir(tmpdir)
EDIT: I should make it clear that, just because the mktemp() vulnerability is averted by this, there are still the other usual security issues that need to be considered; e.g. an attacker could create the fifo (if they had suitable permissions) before your program did which could cause your program to crash if errors/exceptions are not properly handled.
You may find it handy to use the following context manager, which creates and removes the temporary file for you:
import os
import tempfile
from contextlib import contextmanager
#contextmanager
def temp_fifo():
"""Context Manager for creating named pipes with temporary names."""
tmpdir = tempfile.mkdtemp()
filename = os.path.join(tmpdir, 'fifo') # Temporary filename
os.mkfifo(filename) # Create FIFO
try:
yield filename
finally:
os.unlink(filename) # Remove file
os.rmdir(tmpdir) # Remove directory
You can use it, for example, like this:
with temp_fifo() as fifo_file:
# Pass the fifo_file filename e.g. to some other process to read from.
# Write something to the pipe
with open(fifo_file, 'w') as f:
f.write("Hello\n")
How about using
d = mkdtemp()
t = os.path.join(d, 'fifo')
If it's for use within your program, and not with any externals, have a look at the Queue module. As an added benefit, python queues are thread-safe.
Effectively, all that mkstemp does is run mktemp in a loop and keeps attempting to exclusively create until it succeeds (see stdlib source code here). You can do the same with os.mkfifo:
import os, errno, tempfile
def mkftemp(*args, **kwargs):
for attempt in xrange(1024):
tpath = tempfile.mktemp(*args, **kwargs)
try:
os.mkfifo(tpath, 0600)
except OSError as e:
if e.errno == errno.EEXIST:
# lets try again
continue
else:
raise
else:
# NOTE: we only return the path because opening with
# os.open here would block indefinitely since there
# isn't anyone on the other end of the fifo.
return tpath
else:
raise IOError(errno.EEXIST, "No usable temporary file name found")
Why not just use mkstemp()?
For example:
import tempfile
import os
handle, filename = tempfile.mkstemp()
os.mkfifo(filename)
writer = open(filename, os.O_WRONLY)
reader = open(filename, os.O_RDONLY)
os.close(handle)

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