Subprocess. Calledprocesserror: What *Is* the Error?
Import Subprocess Cmd = "Grep -R * | Grep Jquery" Print Cmd Subprocess. Check_Output(Cmd, Shell=True) Subprocess. Calledprocesserror: Command 'Grep -R * | Grep...
import subprocess
cmd = "grep -r * | grep jquery"
print cmd
subprocess.check_output(cmd, shell=True)
subprocess.CalledProcessError: Command 'grep -r * | grep jquery' returned non-zero exit status 1
I can execute that command in my shell without issues. How can I see the actual error in python?
The snippet is part of a larger script which takes multiple arguments and chains the grep commands + adds some excludes (I don't need to grep log files or minified JavaScript. Hence the pedantic syntax.
Python 2.7.10
2 Answers
If the return code was non-zero it raises a
CalledProcessError. TheCalledProcessErrorobject will have the return code in thereturncodeattribute and any output in theoutputattribute.
import subprocess
cmd = "grep -r * | grep jquery"
print cmd
try:
subprocess.check_output(cmd, shell=True)
except subprocess.CalledProcessError as e:
print e.returncode
print e.output
Of error message was printed to stderr, you need keyword argument stderr=subprocess.STDOUT.
There is no other source of 'what went wrong' besides return code and stdout / stderr.
"non-zero exit status" means that the command you ran indicated a status other than success. For grep, the documentation explicitly indicates that an exit status of 1 indicates no lines were found, whereas an exit status more than 1 indicates that some other error took place.
To quote the manual:
EXIT STATUS - The grep utility exits with one of the following values:
0 One or more lines were selected. 1 No lines were selected. >1 An error occurred.
By the way -- if you want to look for the string jquery in all files under the current directory (recursively), use grep -r jquery .; grep -r * searches for the name of the first file in your directory inside the contents of all other files in your directory.
Alexander Ross has covered the video game industry for a decade, writing deep dives on game design, esports tournaments, VR developments, and gaming culture.
