I'm trying to run a bash-command in python where the bash-command saves data to a file rather than displaying it. An example of such command is
$ echo 'foo' > bar.txt
currently my code looks like the following
process = subprocess.Popen(bashCommand.split(), stdout=subprocess.PIPE)
process.communicate()
As I run the python-code no bar.txt is generated. Any idea on how to save the data from the bash-script? The data should not be displayed only saved.
By default, subprocess.Popen() does not run the command via the shell, and therefore I/O redirection operators have no special meaning -- they are treated as ordinary arguments. The easiest way to achieve what you're after is to make it use the shell. With Popen(), you would pass shell=True, and you would not split the command string:
process = subprocess.Popen(bashCommand, stdout=subprocess.PIPE, shell=True)
You should also consider whether the subprocess.call() (Python 2) or subprocess.run() (Python 3) convenience functions offer any advantage to you. It's not clear whether they do, however; in particular, you would need to use the same shell argument in both those cases as well.
Use print(). Simple as that. Anything that would normally be printed to the console will instead be printed to a file, because of the > command.
~$ python3.5 your_script.py > bar.txt
If you do not want to run your python script with >, then you will need to use python’s file operations to write a string version of your data to a file:
with open('bar.txt', 'w') as F:
F.write(data)
>and shell-builtins likeecho, requirebash. So addshell=Trueto yourPopen.stdoutargument if you redirect the commands output with>.