I tried to filter a file that was generated by a function in a python script:
out = subprocess.check_output(["sed","-n","'s/pattern/&/p'",oldFile,">",newFile])
However, I got the followong error about my command:
returned non-zero exit status 1
What is wrong?
As devnull stated, the > is interpreted by the shell. Since it is better to avoid using shell=True, use the stdout parameter instead:
import subprocess
with open(newFile, 'w') as newFile:
subprocess.check_call(
["sed", "-n", "s/S/&/p", oldFile], stdout=newFile)
check_output, the stdout argument is not allowed as it is used internally. Use Popen instead.
call() or check_call().newFile is not a string. Use the with open(...) as newFile statement.You are using > redirections, which require a shell to interpret the syntax.
When you are redirecting the output of sed, there is no point is using check_output here. Use subprocess.call() or subprocess.check_call() instead and verify the return code.
Either run the command through the shell:
import pipes
out = subprocess.call("sed -n 's/S/&/p' {} > {}".format(
pipes.quote(oldFile), pipes.quote(newFile), shell=True)
or use a pipe:
with open(newFile, 'w') as pipetarget:
out = subprocess.call(["sed", "-n", "s/S/&/p", oldFile],
stdout=pipetarget)
Note that you shouldn't use quotes on the 's/S/&/p' string when used as a separate argument in the argument list; when not passing that to the shell it doesn't need escaping from shell parsing either.
