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How can I make one python file run another? [duplicate]
(8 answers)
How to redirect output with subprocess in Python?
(6 answers)
Closed 3 years ago.
I found a script online which converts a file from one specific extension to another, I am trying to utilize subprocess.call and have had no luck so far.
I am trying to use subprocess.call to convert a file in a directory.
I successfully managed to perform this in the terminal and am now trying to execute this in python as part of a program.
For the arguments, I am giving 'python' the name of the script, the file I want to convert and then the new name once it has been converted.
subprocess.call(["python", "converter.py", "file1.txt", ">", "file1converted.xml"])
Am I using subprocess.call in the correct manner? I can't seem to find anywhere on how to perform what I'm trying to do, also if possible I would like to find out a way on how I can convert a file without specifying the new name after conversion, but instead using change the 'file1.txt' to '.xml' once done.
There are two ways to do this, the first is the way you did it but you should add shell=True among the parameter. Do not use shell=True if the shell command is coming from an outside source, cause that would a huge security risk
subprocess.call(["python", "converter.py", "file1.txt", ">", "file1converted.xml"], shell=True)
The other way do this is to make use of Popen which I PERSONALLY prefer
subprocess.Popen(["python", "converter.py", "file1.txt", ">", "file1converted.xml"])
Related
This question already has an answer here:
Using subprocess.Popen (shell=True) with windows folders
(1 answer)
Closed 2 years ago.
The following code can open the test.txt file with notepad
subprocess.Popen(['start','test.txt'],shell=True)
But this won't open a file with a space in its name like 'the test.txt'.
I've tried using raw string(r'...'), double quote on cmd, '%20' to substitute the space, but none of that works.
Passing a list of arguments with shell=True happens to generally work on Windows, but is really never correct. Of course, start is a shell (cmd) command, so you need a shell here; but then, you also need to quote the string for the shell.
subproces.run('start "the test.txt"', shell=True)
Notice also that I switched to subprocess.run(); you generally want to avoid raw Popen whenever you can, as also suggested in the documentation.
It's much easier to rename the file with an underscore or dash etc.
I had a similar issue once with a client. I'm fairly certain we concluded by renaming by hand all of the necessary files to replace a space with an underscore.
Unless python have released a patch (or indeed, I was oblivious), I think it may be impossible.
Python reads a space and goes "okay, thats that command, what's next?" and then reads whatever follows the space, excluding certain things like string variables.
Take these lines
import os
os.system("start EXCEL.EXE my workbook.xlsb")
Python of course imports the os module here, then in line two it runs the os.system command with the parameters; start, EXCEL.EXE, my, workbook.xlsb
in fact it doesn't, once it reaches the filename "my" without an extension it quits and throws an error in the shell.
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read subprocess stdout line by line
(10 answers)
Closed 16 days ago.
I just want to use os.system("dir") and also be able to save the text outputted to a variable. I tried using sys.stdout.read() but running sys.stdout.readable() returns False. Do you know how I can read from the terminal?
using os library:
info = os.popen('dir').read()
You can use the subprocess.check_output method
Example
import subprocess as sp
stdout = sp.check_output("dir")
print(stdout)
There is a bit of confusion here about the different streams, and possibly a better way to do things.
For the specific case of dir, you can replace the functionality you want with the os.listdir function, or better yet os.scandir.
For the more general case, you will not be able to read an arbitrary stdout stream. If you want to do that, you'll have to set up a subprocess whose I/O streams you control. This is not much more complicated than using os.system. you can use subprocess.run, for example:
content = subprocess.run("dir", stdout=subprocess.PIPE, check=True).stdout
The object returned by run has a stdout attribute that contains everything you need.
If you want to read just go with
x = input()
This reads a one line from the terminal. x is a string by default, but you can cast it, say to int, like so
x = int(x)
This question already has answers here:
How do I read from stdin?
(25 answers)
Closed 6 years ago.
I am doing small project in which I have to read the file from STDIN.
I am not sure what it means, what I asked the professor he told me,
there is not need to open the file and close like we generally do.
sFile = open ( "file.txt",'r')
I dont have to pass the file as a argument.
I am kind of confused what he wants.
The stdin takes input from different sources - depending on what input it gets.
Given a very simple bit of code for illustration (let's call it: script.py):
import sys
text = sys.stdin.read()
print text
You can either pipe your script with the input-file like so:
$ more file.txt | script.py
In this case, the output of the first part of the pipeline - which is the content of the file - is assigned to our variable(in this case text, which gets printed out eventually).
When left empty (i.e. without any additional input) like so:
$ python script.py
It let's you write the input similar to the input function and assigns the written input to the defined variable(Note that this input-"window" is open until you explicitly close it, which is usually done with Ctrl+D).
import sys, then sys.stdin will be the 'file' you want which you can use like any other file (e.g. sys.stdin.read()), and you don't have to close it. stdin means "standard input".
Might be helpful if you read through this post, which seems to be similar to yours.
'stdin' in this case would be the argument on the command line coming after the python script, so python script.py input_file. This input_file would be the file containing whatever data you are working on.
So, you're probably wondering how to read stdin. There are a couple of options. The one suggested in the thread linked above goes as follows:
import fileinput
for line in fileinput.input():
#read data from file
There are other ways, of course, but I think I'll leave you to it. Check the linked post for more information.
Depending on the context of your assignment, stdin may be automatically sent into the script, or you may have to do it manually as detailed above.
This question already has answers here:
Formatting a command in python subprocess popen
(2 answers)
Closed 7 years ago.
I have a bunch of different text files, and am trying to sort the texts into one file. I am using python's subprocess, and I wrote the following code
command_line = "sort -m 1.txt 2.txt > a.txt"
args = shlex.split(command_line)
subprocess.call(args)
and the subprocess.call(args) returned 2 as a result, and nothing was written in a.txt. Anything wrong with my code?
If you want to use the shell redirection operator > in your command line, you have to pass shell=True to subprocess.call. Otherwise, '>' and 'a.txt' are passed as command line arguments to sort. With shell=True, the command line is passed to and interpreted by an actual shell, and you should therefore not shlex.split it. It may be easier to use os.system instead of subprocess.call, which uses a shell by default.
This question already has answers here:
Read from File, or STDIN
(9 answers)
Closed 21 days ago.
When writing text-oriented command line programs in Python, I often want to read either all the files passed on the command line, or (XOR) standard input (like Unix cat does, or Perl's <>). So, I say
if len(args) == 0: # result from optparse
input = sys.stdin
else:
input = itertools.chain(*(open(a) for a in args))
Is this the Pythonic way of doing this, or did my miss some part of the library?
You need fileinput.
A standard use case is:
import fileinput
for line in fileinput.input():
process(line)
In Python 3, argparse handles filetype objects very nicely. It's an extremely powerful module and the docs come with many examples, so it's easy to quickly write the code you want. (How Pythonic!)
You may also benefit from this StackOverflow question about using argparse to optionally read from stdin.