writing command line output to file

Question

I am writing a script to clean up my desktop, moving files based on file type. The first step, it would seem, is to ls -1 /Users/user/Desktop (I'm on Mac OSX). So, using Python, how would I run a command, then write the output to a file in a specific directory? Since this will be undocumented, and I'll be the only user, I don't mind (prefer?) if it uses os.system().

What files do you want to move? Take a look at http://docs.python.org/library/shutil.html for file operations using Python. — , Jan 25 '12 at 13:32
If you use shell scripts, read more about pipes and redirection. — Some programmer dude, Jan 25 '12 at 13:35
I am not talking about creating a seperate .sh file. A combination of `for`, `if`, `file` would be enough. — Shiplu Mokaddim, Jan 25 '12 at 13:37
If you're not creating a shell script you shouldn't be using `ls`. In fact, even if you are creating a shell script your should be using `find` for this. — sorpigal, Jan 25 '12 at 14:16

score 23 · Accepted Answer · answered Jan 25 '12 at 13:37

23

You can redirect standard output to any file using > in command.

$ ls /Users/user/Desktop > out.txt

Using python,

os.system('ls /Users/user/Desktop > out.txt')

However, if you are using python then instead of using ls command you can use os.listdir to list all the files in the directory.

path = '/Users/user/Desktop'
files = os.listdir(path)
print files

answered Jan 25 '12 at 13:37

taskinoor

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ImportError: No module named system. – McLan May 26 '16 at 13:54
@Suda.nese how are trying to import? What is your Python version? – taskinoor May 26 '16 at 19:22

score 3 · Answer 2 · answered Jan 25 '12 at 13:39

After skimming the python documentation to run shell command and obtain the output you can use the subprocess module with the check_output method.

After that you can simple write that output to a file with the standard Python IO functions: File IO in python.

score 1 · Answer 3 · answered Jan 25 '12 at 15:13

To open a file, you can use the f = open(/Path/To/File) command. The syntax is f = open('/Path/To/File', 'type') where 'type' is r for reading, w for writing, and a for appending. The commands to do this are f.read() and f.write('content_to_write'). To get the output from a command line command, you have to use popen and subprocess instead of os.system(). os.system() doesn't return a value. You can read more on popen here.

writing command line output to file

3 Answers3

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