Python 实用宝典

Question 1

The question, number 10501247, in stackoverflow gives answer how to create temporary file in Python.
I only need to have temporary file name in my case.
Calling tempfile.NamedTemporaryFile() returns file handle after actual file creation.
Is there way to get file name only?

# Trying to get temp file path
tf = tempfile.NamedTemporaryFile()
temp_file_name = tf.name
tf.close()
# Here is my real purpose to get the temp_file_name
f = gzip.open(temp_file_name ,'wb')
...

Question 2

If you want a temp file name only you can call inner tempfile function _get_candidate_names():

import tempfile

temp_name = next(tempfile._get_candidate_names())
% e.g. px9cp65s

Calling next again, will return another name, etc. This does not give you the path to temp folder. To get default ‘tmp’ directory, use:

defult_tmp_dir = tempfile._get_default_tempdir()
% results in: /tmp

Question 3

I think the easiest, most secure way of doing this is something like:

path = os.path.join(tempfile.mkdtemp(), 'something')

A temporary directory is created that only you can access, so there should be no security issues, but there will be no files created in it, so you can just pick any filename you want to create in that directory.

edit: In Python 3 you can now use tempfile.TemporaryDirectory() as a context manager to handle deletion for you:

with tempfile.TemporaryDirectory() as tmp:
  path = os.path.join(tmp, 'something')
  # use path

Question 4

It may be a little late, but is there anything wrong with this?

import tempfile
with tempfile.NamedTemporaryFile(dir='/tmp', delete=False) as tmpfile:
    temp_file_name = tmpfile.name
f = gzip.open(temp_file_name ,'wb')

Question 5

tempfile.mktemp() do this.

But note that it’s deprecated. However it will not create the file and it is a public function in tempfile compared to using the _get_candidate_names().

The reason it’s deprecated is due to the time gap between calling this and actually trying to create the file. However in my case the chance of that is so slim and even if it would fail that would be acceptable. But it’s up to you to evaluate for your usecase.

Question 6

Combining the previous answers, my solution is:

def get_tempfile_name(some_id):
    return os.path.join(tempfile.gettempdir(), next(tempfile._get_candidate_names()) + "_" + some_id)

Make some_id optional if not needed for you.

Question 7

As Joachim Isaksson said in the comments, if you just get a name you may have problems if some other program happens to use that name before your program does. The chances are slim, but not impossible.

So the safe thing to do in this situation is to use the full GzipFile() constructor, which has the signature GzipFile( [filename[, mode[, compresslevel[, fileobj]]]]). So you can pass it the open fileobj, and a filename as well, if you like. See the gzip docs for details.

Question 8

how to create a temporary directory and get the path / file name in python

Question 9

Use the mkdtemp() function from the tempfile module:

import tempfile
import shutil

dirpath = tempfile.mkdtemp()
# ... do stuff with dirpath
shutil.rmtree(dirpath)

Question 10

In Python 3, TemporaryDirectory in the tempfile module can be used.

This is straight from the examples:

import tempfile
with tempfile.TemporaryDirectory() as tmpdirname:
     print('created temporary directory', tmpdirname)
# directory and contents have been removed

If you would like to keep the directory a bit longer, then something like this could be done (not from the example):

import tempfile

temp_dir = tempfile.TemporaryDirectory()
print(temp_dir.name)
# use temp_dir, and when done:
temp_dir.cleanup()

The documentation also says that “On completion of the context or destruction of the temporary directory object the newly created temporary directory and all its contents are removed from the filesystem.” So at the end of the program, for example, Python will clean up the directory if it wasn’t explicitly removed. Python’s unittest may complain of ResourceWarning: Implicitly cleaning up <TemporaryDirectory... if you rely on this, though.

Question 11

To expand on another answer, here is a fairly complete example which can cleanup the tmpdir even on exceptions:

import contextlib
import os
import shutil
import tempfile

@contextlib.contextmanager
def cd(newdir, cleanup=lambda: True):
    prevdir = os.getcwd()
    os.chdir(os.path.expanduser(newdir))
    try:
        yield
    finally:
        os.chdir(prevdir)
        cleanup()

@contextlib.contextmanager
def tempdir():
    dirpath = tempfile.mkdtemp()
    def cleanup():
        shutil.rmtree(dirpath)
    with cd(dirpath, cleanup):
        yield dirpath

def main():
    with tempdir() as dirpath:
        pass # do something here

Question 12

In python 3.2 and later, there is a useful contextmanager for this in the stdlib https://docs.python.org/3/library/tempfile.html#tempfile.TemporaryDirectory

Question 13

If I get your question correctly, you want to also know the names of the files generated inside the temporary directory? If so, try this:

import os
import tempfile

with tempfile.TemporaryDirectory() as tmp_dir:
    # generate some random files in it
     files_in_dir = os.listdir(tmp_dir)

Python 实用宝典

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