If all you need is the stdout output, then take a look at subprocess.check_output(): import subprocess batcmd=”dir” result = subprocess.check_output(batcmd, shell=True) Because you were using os.system(), you’d have to set shell=True to get the same behaviour. You do want to heed the security concerns about passing untrusted arguments to your shell. If you need to … Read more
To save both stdout and stderr to a variable: MYVARIABLE=”$(path/myExcecutable-bin 2>&1)” Note that this interleaves stdout and stderr into the same variable. To save just stderr to a variable: MYVARIABLE=”$(path/myExcecutable-bin 2>&1 > /dev/null)”
I found this to be the only one short, flexible, portable and readable: # This line only if you still care about Python2 from __future__ import print_function import sys def eprint(*args, **kwargs): print(*args, file=sys.stderr, **kwargs) The optional function eprint saves some repetition. It can be used in the same way as the standard print function: … Read more
If you want to execute a command, and get both stderr and stdout, not “merged”, a solution would probably to use proc_open, which provides a great level of control over the command that’s being executed — including a way to pipe stdin/stdout/stderr. And here is an example : let’s consider we have this shell-script, in … Read more
Standard input – this is the file handle that your process reads to get information from you. Standard output – your process writes conventional output to this file handle. Standard error – your process writes diagnostic output to this file handle. That’s about as dumbed-down as I can make it 🙂 Of course, that’s mostly … Read more
You can also put the redirection logic in a contextmanager. import os import sys class RedirectStdStreams(object): def __init__(self, stdout=None, stderr=None): self._stdout = stdout or sys.stdout self._stderr = stderr or sys.stderr def __enter__(self): self.old_stdout, self.old_stderr = sys.stdout, sys.stderr self.old_stdout.flush(); self.old_stderr.flush() sys.stdout, sys.stderr = self._stdout, self._stderr def __exit__(self, exc_type, exc_value, traceback): self._stdout.flush(); self._stderr.flush() sys.stdout = self.old_stdout sys.stderr … Read more
It would be neater to capture the error file thus: ERROR=$(</tmp/Error) The shell recognizes this and doesn’t have to run ‘cat‘ to get the data. The bigger question is hard. I don’t think there’s an easy way to do it. You’d have to build the entire pipeline into the sub-shell, eventually sending its final standard … Read more
Take a look here. It should be: yourcommand &> filename It redirects both standard output and standard error to file filename.
First redirect stderr to stdout — the pipe; then redirect stdout to /dev/null (without changing where stderr is going): command 2>&1 >/dev/null | grep ‘something’ For the details of I/O redirection in all its variety, see the chapter on Redirections in the Bash reference manual. Note that the sequence of I/O redirections is interpreted left-to-right, … Read more
cmd >>file.txt 2>&1 Bash executes the redirects from left to right as follows: >>file.txt: Open file.txt in append mode and redirect stdout there. 2>&1: Redirect stderr to “where stdout is currently going”. In this case, that is a file opened in append mode. In other words, the &1 reuses the file descriptor which stdout currently … Read more