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POUrllib and urllib2 returns "IOError: [Errno socket error] [Errno -2] Name or service not known" but Firefox downloads file with no trouble
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  1. POUrllib and urllib2 returns "IOError: [Errno socket error] [Errno -2] Name or service not known" but Firefox downloads file with no trouble
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    copied!<p>I am trying to download GRIB data (binary weather forecast data) from the National Weather Service. I have written Python code to format the HTTP string to get data for today, looking 12 hours ahead.</p> <p>The Python code returns the HTTP string, then attempts to use urllib.urlopen to download the data. Now, if I paste the HTTP string into Firefox, the GRIB file downloads. If I try to use urllib.urlopen, I get the following:</p> <pre><code>Traceback (most recent call last): File "/home/dantayaga/bovine_aerospace/dev/grib_get.py", line 67, in &lt;module&gt; webf=urllib.urlopen(griburl) File "/usr/lib/python2.7/urllib.py", line 86, in urlopen return opener.open(url) File "/usr/lib/python2.7/urllib.py", line 207, in open return getattr(self, name)(url) File "/usr/lib/python2.7/urllib.py", line 344, in open_http h.endheaders(data) File "/usr/lib/python2.7/httplib.py", line 954, in endheaders self._send_output(message_body) File "/usr/lib/python2.7/httplib.py", line 814, in _send_output self.send(msg) File "/usr/lib/python2.7/httplib.py", line 776, in send self.connect() File "/usr/lib/python2.7/httplib.py", line 757, in connect self.timeout, self.source_address) File "/usr/lib/python2.7/socket.py", line 553, in create_connection for res in getaddrinfo(host, port, 0, SOCK_STREAM): IOError: [Errno socket error] [Errno -2] Name or service not known </code></pre> <p>Here is the HTTP string I am using:</p> <p><a href="http://nomads.ncep.noaa.gov/cgi-bin/filter_gfs_hd.pl?file=gfs.t06z.mastergrb2f12&amp;lev_1000_mb=on&amp;lev_975_mb=on&amp;lev_950_mb=on&amp;lev_925_mb=on&amp;lev_900_mb=on&amp;lev_850_mb=on&amp;lev_800_mb=on&amp;lev_750_mb=on&amp;lev_700_mb=on&amp;lev_650_mb=on&amp;lev_600_mb=on&amp;lev_550_mb=on&amp;lev_500_mb=on&amp;lev_450_mb=on&amp;lev_400_mb=on&amp;lev_350_mb=on&amp;lev_300_mb=on&amp;lev_250_mb=on&amp;lev_200_mb=on&amp;lev_150_mb=on&amp;lev_100_mb=on&amp;lev_70_mb=on&amp;lev_30_mb=on&amp;lev_20_mb=on&amp;lev_10_mb=on&amp;var_HGT=on&amp;var_RH=on&amp;var_TMP=on&amp;var_UGRD=on&amp;var_VGRD=on&amp;var_VVEL=onleftlon=-90rightlon=90toplat=90bottomlat-90&amp;dir=%2Fgfs.2012070706%2Fmaster" rel="nofollow">http://nomads.ncep.noaa.gov/cgi-bin/filter_gfs_hd.pl?file=gfs.t06z.mastergrb2f12&amp;lev_1000_mb=on&amp;lev_975_mb=on&amp;lev_950_mb=on&amp;lev_925_mb=on&amp;lev_900_mb=on&amp;lev_850_mb=on&amp;lev_800_mb=on&amp;lev_750_mb=on&amp;lev_700_mb=on&amp;lev_650_mb=on&amp;lev_600_mb=on&amp;lev_550_mb=on&amp;lev_500_mb=on&amp;lev_450_mb=on&amp;lev_400_mb=on&amp;lev_350_mb=on&amp;lev_300_mb=on&amp;lev_250_mb=on&amp;lev_200_mb=on&amp;lev_150_mb=on&amp;lev_100_mb=on&amp;lev_70_mb=on&amp;lev_30_mb=on&amp;lev_20_mb=on&amp;lev_10_mb=on&amp;var_HGT=on&amp;var_RH=on&amp;var_TMP=on&amp;var_UGRD=on&amp;var_VGRD=on&amp;var_VVEL=onleftlon=-90rightlon=90toplat=90bottomlat-90&amp;dir=%2Fgfs.2012070706%2Fmaster</a></p> <p>If you are testing this string in Firefox and it's not working, change "20120707" to today's date and "06" to "00" and it should work.</p> <p>My question is simple (I think): why does this work in Firefox and not with urllib? </p> <p>Here is the code I use to generate the http string and then attempt to download the result:</p> <pre><code>#Get GRIB files import urllib forecast_time='06' #What time the forecast is (00, 06, 12, 18) forecast_hours='12' #How many hours ahead to forecast (2 or 3 digits) forecast_date='20120707' #What date the forecast is for yyyymmdd top_lat=90 #Top of bounding box (North) bottom_lat=-90 #Bottom of bounding box (South) left_lon=-90 #Left of bounding box (West) right_lon=90 #Right of bounding box (East) griburl='http://nomads.ncep.noaa.gov/cgi-bin/filter_gfs_hd.pl?' griburl=griburl+'file=gfs.t'+str(forecast_time)+'z.mastergrb2f' griburl=griburl+forecast_hours #Select atmospheric levels griburl=griburl+'&amp;lev_1000_mb=on' #1000 mb level griburl=griburl+'&amp;lev_975_mb=on' #975 mb level griburl=griburl+'&amp;lev_950_mb=on' #950 mb level griburl=griburl+'&amp;lev_925_mb=on' #925 mb level griburl=griburl+'&amp;lev_900_mb=on' #900 mb level griburl=griburl+'&amp;lev_850_mb=on' #850 mb level griburl=griburl+'&amp;lev_800_mb=on' #800 mb level griburl=griburl+'&amp;lev_750_mb=on' #750 mb level griburl=griburl+'&amp;lev_700_mb=on' #700 mb level griburl=griburl+'&amp;lev_650_mb=on' #650 mb level griburl=griburl+'&amp;lev_600_mb=on' #600 mb level griburl=griburl+'&amp;lev_550_mb=on' #550 mb level griburl=griburl+'&amp;lev_500_mb=on' #500 mb level griburl=griburl+'&amp;lev_450_mb=on' #450 mb level griburl=griburl+'&amp;lev_400_mb=on' #400 mb level griburl=griburl+'&amp;lev_350_mb=on' #350 mb level griburl=griburl+'&amp;lev_300_mb=on' #300 mb level griburl=griburl+'&amp;lev_250_mb=on' #250 mb level griburl=griburl+'&amp;lev_200_mb=on' #200 mb level griburl=griburl+'&amp;lev_150_mb=on' #150 mb level griburl=griburl+'&amp;lev_100_mb=on' #100 mb level griburl=griburl+'&amp;lev_70_mb=on' #70 mb level griburl=griburl+'&amp;lev_30_mb=on' #30 mb level griburl=griburl+'&amp;lev_20_mb=on' #20 mb level griburl=griburl+'&amp;lev_10_mb=on' #10 mb level #Select variables griburl=griburl+'&amp;var_HGT=on' #Height (geopotential m) griburl=griburl+'&amp;var_RH=on' #Relative humidity (%) griburl=griburl+'&amp;var_TMP=on' #Temperature (K) griburl=griburl+'&amp;var_UGRD=on' #East-West component of wind (m/s) griburl=griburl+'&amp;var_VGRD=on' #North-South component of wind (m/s) griburl=griburl+'&amp;var_VVEL=on' #Vertical Windspeed (Pa/s) #Select bounding box griburl=griburl+'leftlon='+str(left_lon) griburl=griburl+'rightlon='+str(right_lon) griburl=griburl+'toplat='+str(top_lat) griburl=griburl+'bottomlat'+str(bottom_lat) #Select date and time griburl=griburl+'&amp;dir=%2Fgfs.'+forecast_date+forecast_time+'%2Fmaster' print(griburl) print('Downloading GRIB file for date '+forecast_date+' time ' +forecast_time + ', forecasting '+forecast_hours+' hours ahead...') webf=urllib.urlopen(griburl) local_filename=forecast_date+'_'+forecast_time+'_'+forecast_hours+'.grib' localf=open('//home//dantayaga//bovine_aerospace//grib//data//'+local_filename, 'wb') localf.write(webf.read()) print('Requested grib data written to file '+local_filename) </code></pre> <p>Any help is most appreciated. Is there a formatting error that Firefox is catching or something?</p>
 

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