CODEWITHSUNDEEP
shellpython-2.7output
ADJ
ADJ

Reputation: 5282

Python, capture the entire output from shell command

I'm using Python to automate some work I'm doing in machine learning. The machine learning tool I'm using is Vowpal Wabbit and I usually run it from terminal. I'm able to use Python's call(vw_command,shell=True) to run Vowpal Wabbit, but I also want to capture VW's entire shell output. This is what I tried:

output =check_output(vw_command, shell=True)

This is what I see in my Python IDE:

creating quadratic features for pairs: hh hb hp hr  final_regressor = model_vw.vw Num weight bits = 28 learning rate = 0.7 initial_t = 0 power_t = 0.5 decay_learning_rate = 1 creating cache_file = fold1.vw.cache Reading datafile = fold1.vw num sources = 1 average    since         example     example  current  current  current loss      last          counter      weight    label  predict features
0.693147   0.693147            1         1.0  -1.0000   0.0000     1209
0.615108   0.537070            2         2.0  -1.0000  -0.3411     1217
0.527696   0.440284            4         4.0  -1.0000  -0.5287     1217
0.474677   0.421658            8         8.0  -1.0000  -0.9651     1201
0.363831   0.252986           16        16.0  -1.0000  -1.2778     1217
0.259342   0.154852           32        32.0  -1.0000  -2.1993     1209
0.170503   0.081664           64        64.0  -1.0000  -2.5598     1217
0.106260   0.042017          128       128.0  -1.0000  -2.8044     1217
0.083359   0.060457          256       256.0  -1.0000  -8.8870     1217
0.056569   0.029780          512       512.0  -1.0000  -4.4179     1209
0.044556   0.032542         1024      1024.0  -1.0000  -4.0888     1209
0.036272   0.027989         2048      2048.0  -1.0000  -5.3605     1217
0.033533   0.030794         4096      4096.0  -1.0000  -5.7477     1199
0.026593   0.019653         8192      8192.0  -1.0000  -9.1520     1194
0.019215   0.011837        16384     16384.0  -1.0000 -13.8832     1209
0.014147   0.009079        32768     32768.0  -1.0000  -9.5163     1209
0.012523   0.010898        65536     65536.0  -1.0000 -17.4003     1209
0.009721   0.006920       131072    131072.0  -1.0000 -13.1049     1217
0.007038   0.004355       262144    262144.0  -1.0000 -10.1183     1209
0.005340   0.003642       524288    524288.0  -1.0000 -10.7823     1203
0.003909   0.002478      1048576   1048576.0  -1.0000  -9.5997     1209
0.002318   0.000727      2097152   2097152.0  -1.0000 -22.7368     1217

finished run
number of examples per pass = 425000
passes used = 1
weighted example sum = 425000
weighted label sum = -419716
average loss = 236.561
best constant = -0.987572
total feature number = 514554601

But when I look at the variable output it is an empty string ''. How do I capture the entire shell output?

Upvotes: 2

Views: 2897

Answers (3)

polym
polym

Reputation: 658

You can use the sh module, which pretty much is just magic. The output comes right out of the call:

enter image description here

If you don't want to use another module, disregard my answer.

Upvotes: 1

harika
harika

Reputation: 11

import subprocess

cmd = "ls -l"

output = subprocess.Popen(cmd,shell=True, stdout=subprocess.PIPE,stderr=subprocess.STDOUT).stdout.read()

print output

Upvotes: 1

Hackaholic
Hackaholic

Reputation: 19733

use Popen with pipe, here it is:

import subprocess
child = subprocess.Popen('command',shell=True,stdout=subprocess.PIPE)
output = child.communicate()[0]
print output

Upvotes: 3

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