Running wget using subprocess module, the normal output (channel 1) is redirecting to the error channel (channel 2)

Question

def wget_url(url):     
   try:
        wget = subprocess.Popen(["wget "+url],shell=True,stdout=PIPE,stderr=PIPE)
        return wget
   except:
        print("HTTP error")

a=wget_url(url)
a.stdout.readlines() #return an empty string.
a.stderr.readlines() #return the normal output that would be displayed in terminal

is this normal? Why stdout returns nothing?

score 0 · Answer 1 · answered Dec 22 '17 at 13:29

This isn't Python problem but a feature of wget:

 wget url >  stdout.txt 2> stderr.txt

Here stdout.txt is empty and stdout.txt 2> has the screen output with 200 OKetc. This is a well known fact. Diagnostic messages could interfere with piping and therefore are better routed to stderr.

Running wget using subprocess module, the normal output (channel 1) is redirecting to the error channel (channel 2)

1 Answers1