title: How to grep all the data in a specified col from standard output?
body: <p>Now i have a standard output which is printed by my program and displayed on the screen. The outputs looks like the following part:</p>
  
  <pre><code>Parsing command line string 'InputFile = foreman.qcif'.
  Parsing command line string 'NumberReferenceFrames = 1'.
  Parsing command line string 'QPISlice = 24'.
  Parsing command line string 'QPPSlice = 24'.
  
  ------------------------------- JM 11.0 (FRExt) --------------------------------
   Input YUV file                    : foreman.qcif 
   Output H.264 bitstream            : test.264 
   Output YUV file                   : test_rec.yuv 
   YUV Format                        : YUV 4:2:0 
   Frames to be encoded I-P/B        : 150/0
   PicInterlace / MbInterlace        : 0/0
   Transform8x8Mode                  : 1
  -------------------------------------------------------------------------------
    Frame  Bit/pic    QP   SnrY    SnrU    SnrV    Time(ms) MET(ms) Frm/Fld Ref  
  -------------------------------------------------------------------------------
  0000(NVB)     168 
  0000(IDR)   34280   24  39.724  41.720  43.998       286       0    FRM    1
  0002(P)      7432   24  38.857  41.565  43.829       402      99    FRM    1
  0004(P)      8976   24  38.642  41.275  43.698       409      97    FRM    1
  0006(P)      8344   24  38.427  41.266  43.515       407      99    FRM    1
  0008(P)      8224   24  38.609  41.082  43.524       413      94    FRM    1
  0010(P)      7784   24  38.655  40.991  43.235       406      95    FRM    1
  0012(P)      7136   24  38.534  40.687  43.273       411      95    FRM    1
  0014(P)      6688   24  38.464  40.756  43.146       410      92    FRM    1
  0016(P)      7720   24  38.516  40.585  42.851       410      91    FRM    1
  0018(P)      6864   24  38.474  40.631  42.958       411     101    FRM    1
  0020(P)      8392   24  38.433  40.607  42.646       415      99    FRM    1
  0022(P)      9744   24  38.371  40.554  42.498       416      94    FRM    1
  0024(P)      8368   24  38.362  40.531  42.380       417      93    FRM    1
  0026(P)      7904   24  38.414  40.586  42.415       418      95    FRM    1
  0028(P)      8688   24  38.403  40.523  42.366       418      96    FRM    1
  0030(P)      9128   24  38.545  40.390  42.661       416      89    FRM    1
  0032(P)      9664   24  38.399  40.538  42.740       413      88    FRM    1
  0034(P)      8928   24  38.394  40.590  42.852       414      95    FRM    1
  0036(P)     10024   24  38.423  40.562  42.697       415      92    FRM    1
  0038(P)      9320   24  38.442  40.389  42.689       414      94    FRM    1
  0040(P)      7304   24  38.404  40.487  42.884       410      90    FRM    1
  0042(P)      8560   24  38.447  40.590  42.673       411      95    FRM    1
  </code></pre>
  
  <p>.......</p>
  
  <p>Now I only need to process the 4th col of SnrY. </p>
  
  <p>So, my question is how to grep this rol and to store them in a data.txt file?</p>
  
  <p>Then I can use plot tool or Matlab to plot the data trends with these data..</p>
  
  <p>Any advices?  Many thanks for your kind help!</p>
  
  <p>Addition:</p>
  
  <p>Since it needs to pick those data from standard output, do I need to use(add) the command provided by you in the command line to make it works during outputs those data
  ? </p>