stdout.write prefixing spaces when printing

Question

I am trying to grab 802.11 beacons and print them. Printing adds a line whereas stdout prefixes random spaces before/after the channel. Any ideas how to get the line flush to the left without a new line?

def beacon_sniff(pkt):
try:
    sta_oui = pkt.addr2[0:8] # Grab vendor OUI of BSSID
    if pkt.subtype == 8:
        if pkt.addr2 not in ap:
            if pkt.info != "\x00\x00\x00\x00\x00\x00\x00\x00": #Filter out hidden SSID's
                ap.append(pkt.addr2)
                #print '{0:<7} \t {1:<32} \t {2:<20} \t {3:<10} \t {4:<10}'.format(int(ord(pkt[5].info)), pkt.info, pkt.addr2, -(256-ord(pkt[0].notdecoded[-4:-3])), get_vendor(sta_oui))
                sys.stdout.write("{0:<7} \t {1:<32} \t {2:<20} \t {3:<10} \t {4:<10}".format(int(ord(pkt[5].info)), pkt.info, pkt.addr2, -(256-ord(pkt[0].notdecoded[-4:-3])), get_vendor(sta_oui)))
                sys.stdout.flush()
except:         
    pass

stdout:

6            TALKTALK-F148E8...
    6            BTHub3-Z3KP...
  1          BTWifi-X...

print:

6            TALKTALK-F148E8...

6            BTHub3-Z3KP...

1            BTWifi-X...

possible duplicate of [Python print on same line](http://stackoverflow.com/questions/5598181/python-print-on-same-line) — mbomb007, Jan 22 '15 at 22:25
Maybe it's something with the `format` function. I'd try to debug by printing one piece at a time, using the `print` function with commas. — mbomb007, Jan 22 '15 at 22:54

score 1 · Answer 1 · answered Jan 22 '15 at 22:39

1

The "random" spaces are there because you're using \t in the output string. That character in most terminals will move to next multiple of 8.

This means that sometimes adding a single space will end up adding 7 more spaces.

answered Jan 22 '15 at 22:39

6502

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why would it be adding this at the beginning of the string? – Jordyc Jan 22 '15 at 23:03
You are not adding a newline `\n` at the end, therefore the output will wrap every 80 chars (or whatever is the horizontal size of the terminal). – 6502 Jan 22 '15 at 23:06

score 0 · Answer 2 · answered Jan 22 '15 at 22:28

Go back to using the print function. To keep it from adding a new line at the end, put a comma at the end of your print statement.

This prints on two lines:

print "Hello"
print "world!"

But this prints it on the same line:

print "Hello",
print "world!"

stdout.write prefixing spaces when printing

2 Answers2