issues672 portstat support clear or stat one port

[yangshp1987]

- What I did

- How I did it

- How to verify it

- Previous command output (if the output of a command-line utility has changed)

root@sonic:/usr/lib/python2.7/dist-packages/utilities_common# portstat
      IFACE    STATE              RX_OK    RX_BPS    RX_UTIL             RX_ERR    RX_DRP             RX_OVR              TX_OK    TX_BPS    TX_UTIL             TX_ERR    TX_DRP             TX_OVR
-----------  -------  -----------------  --------  ---------  -----------------  --------  -----------------  -----------------  --------  ---------  -----------------  --------  -----------------
  Ethernet0        D  2,114,316,102,605  0.00 B/s      0.00%  1,348,839,001,261         0    240,203,941,461  2,285,404,265,546  0.00 B/s      0.00%    350,270,733,614         0    365,833,058,905
  Ethernet4        D  2,691,813,640,701  0.00 B/s      0.00%  2,044,188,179,972         0    918,880,245,693  2,181,295,289,532  0.00 B/s      0.00%    897,771,714,278         0    349,470,841,325
  Ethernet8        D  2,374,007,146,306  0.00 B/s      0.00%  2,390,883,192,821         0    300,393,297,279  1,627,669,035,123  0.00 B/s      0.00%    569,485,240,059         0     94,351,277,622
 Ethernet12        D  2,837,410,479,240  0.00 B/s      0.00%  1,288,679,352,877         0    417,034,819,423  2,355,856,598,490  0.00 B/s      0.00%    734,301,611,491         0    948,060,651,671
 Ethernet16        D  2,740,197,878,414  0.00 B/s      0.00%  2,621,988,106,679         0    777,300,884,914  3,703,464,652,903  0.00 B/s      0.00%    887,225,841,025         0    897,597,575,532
 Ethernet20        D  2,814,755,876,466  0.00 B/s      0.00%  2,090,398,383,057         0    201,661,521,758  2,217,451,593,841  0.00 B/s      0.00%    465,189,422,827         0    272,088,163,282
 Ethernet24        D  3,146,667,783,942  0.00 B/s      0.00%  1,934,887,886,049         0    957,300,534,075  2,717,412,392,361  0.00 B/s      0.00%    982,589,839,642         0    913,482,411,127
 Ethernet28        D  2,151,108,084,063  0.00 B/s      0.00%  2,117,863,285,888         0    101,705,702,270  3,001,875,678,191  0.00 B/s      0.00%    513,665,458,611         0    375,204,956,799
 Ethernet32        D  3,264,128,115,095  0.00 B/s      0.00%  2,624,579,657,640         0    938,695,826,347  2,237,579,139,102  0.00 B/s      0.00%    182,276,693,611         0    754,756,455,119
 Ethernet36        D  1,388,605,008,954  0.00 B/s      0.00%  1,032,370,865,099         0     67,305,471,435  2,815,768,604,754  0.00 B/s      0.00%    538,419,259,559         0    549,265,778,187
 Ethernet40        D  3,097,977,734,127  0.00 B/s      0.00%  1,468,197,728,764         0    823,433,939,818  3,508,559,915,050  0.00 B/s      0.00%    587,482,884,382         0  1,081,724,304,026
 Ethernet44        D  2,767,655,338,603  0.00 B/s      0.00%  1,498,689,796,523         0    528,258,661,030  2,802,804,323,061  0.00 B/s      0.00%    268,044,074,967         0    985,407,927,222
 Ethernet48        D  2,713,759,303,527  0.00 B/s      0.00%  1,575,788,134,426         0    789,860,308,069  3,607,712,273,047  0.00 B/s      0.00%    377,545,005,044         0  1,081,657,845,849
 Ethernet52        D  3,491,256,687,576  0.00 B/s      0.00%  2,455,430,724,492         0    649,704,836,349  2,034,750,688,109  0.00 B/s      0.00%    952,884,393,613         0    315,633,409,910
 Ethernet56        D  3,815,244,977,812  0.00 B/s      0.00%  2,206,045,440,664         0    833,159,166,405  3,160,122,412,616  0.00 B/s      0.00%    684,300,115,581         0    770,213,928,771
 Ethernet60        D  1,997,494,429,391  0.00 B/s      0.00%  1,864,667,304,178         0    291,911,265,790  1,861,622,066,234  0.00 B/s      0.00%  1,069,437,999,055         0    362,924,039,503
 Ethernet64        D  2,864,520,686,110  0.00 B/s      0.00%  1,987,087,532,827         0  1,016,464,124,343  2,350,321,984,601  0.00 B/s      0.00%    197,799,685,855         0    663,081,974,515
 Ethernet68        D  2,457,331,450,939  0.00 B/s      0.00%  1,086,411,965,452         0    276,075,216,177  2,365,961,700,054  0.00 B/s      0.00%    463,184,691,071         0    329,351,291,855
 Ethernet72        D  2,451,628,732,112  0.00 B/s      0.00%  2,895,197,231,278         0    891,062,939,606  2,179,839,493,977  0.00 B/s      0.00%    848,079,426,031         0  1,090,256,878,359
 Ethernet76        D  2,347,897,820,366  0.00 B/s      0.00%  2,041,630,789,394         0    514,724,719,408  2,358,488,156,406  0.00 B/s      0.00%    406,880,906,697         0    334,059,065,174
 Ethernet80        D  2,926,735,092,806  0.00 B/s      0.00%  1,122,260,750,722         0    826,166,565,945  1,693,901,621,155  0.00 B/s      0.00%    495,798,081,400         0    505,079,855,596
 Ethernet84        D  2,933,868,293,010  0.00 B/s      0.00%  1,290,644,152,020         0    445,964,963,165  2,384,252,965,964  0.00 B/s      0.00%    506,265,993,045         0    540,953,533,559
 Ethernet88        D  2,182,583,297,346  0.00 B/s      0.00%  1,273,888,687,805         0    936,159,697,358  1,747,388,128,703  0.00 B/s      0.00%  1,073,160,848,709         0    352,879,195,439
 Ethernet92        D  3,123,337,390,488  0.00 B/s      0.00%  1,279,978,561,846         0  1,090,904,621,041  2,167,755,463,604  0.00 B/s      0.00%    646,247,863,199         0    907,594,852,899
 Ethernet96        D  2,498,098,397,014  0.00 B/s      0.00%  1,024,608,760,869         0    506,107,608,933  1,427,913,220,971  0.00 B/s      0.00%    925,529,644,511         0    387,977,174,644
Ethernet100        D  2,151,588,404,300  0.00 B/s      0.00%  2,043,650,224,188         0    211,058,890,181  1,037,030,137,751  0.00 B/s      0.00%    407,582,623,069         0    350,397,748,572
Ethernet104        D  2,766,180,645,268  0.00 B/s      0.00%  1,247,823,628,279         0    936,134,528,782  1,032,169,932,563  0.00 B/s      0.00%    942,725,897,517         0     25,095,755,645
Ethernet108        D  2,709,040,331,509  0.00 B/s      0.00%  2,320,551,242,013         0    227,169,530,331  1,417,086,686,815  0.00 B/s      0.00%    373,890,037,460         0    332,120,030,583
Ethernet112        D  3,403,033,141,593  0.00 B/s      0.00%  1,649,128,632,588         0    920,922,100,015  2,466,182,849,097  0.00 B/s      0.00%    956,743,750,741         0    884,191,520,114
Ethernet116        D  2,528,901,607,694  0.00 B/s      0.00%  2,370,743,157,408         0  1,031,319,408,954  2,128,075,768,126  0.00 B/s      0.00%  1,092,823,285,644         0    470,131,113,822
Ethernet120        D  2,948,185,590,179  0.00 B/s      0.00%  2,049,815,555,275         0  1,053,405,440,221  1,970,717,268,003  0.00 B/s      0.00%    403,030,144,375         0    225,996,667,696
Ethernet124        D  3,291,319,936,510  0.00 B/s      0.00%  1,816,917,691,792         0    466,777,779,120  3,318,967,557,029  0.00 B/s      0.00%    178,949,930,691         0    187,875,449,549

- New command output (if the output of a command-line utility has changed)

root@sonic:/usr/lib/python2.7/dist-packages/utilities_common# portstat -P Ethernet24 -c
Cleared counters
root@sonic:/usr/lib/python2.7/dist-packages/utilities_common# portstat -i Ethernet24
Last cached time was 2019-09-26 02:41:51.528075
     IFACE    STATE    RX_OK    RX_BPS    RX_UTIL    RX_ERR    RX_DRP    RX_OVR    TX_OK    TX_BPS    TX_UTIL    TX_ERR    TX_DRP    TX_OVR
----------  -------  -------  --------  ---------  --------  --------  --------  -------  --------  ---------  --------  --------  --------
Ethernet24        D        0  0.00 B/s      0.00%         0         0         0        0  0.00 B/s      0.00%         0         0         0

root@sonic:/usr/lib/python2.7/dist-packages/utilities_common# portstat
Last cached time was 2019-09-26 02:41:51.528075
      IFACE    STATE              RX_OK    RX_BPS    RX_UTIL             RX_ERR    RX_DRP             RX_OVR              TX_OK    TX_BPS    TX_UTIL             TX_ERR    TX_DRP             TX_OVR
-----------  -------  -----------------  --------  ---------  -----------------  --------  -----------------  -----------------  --------  ---------  -----------------  --------  -----------------
  Ethernet0        D  2,114,316,102,605  0.00 B/s      0.00%  1,348,839,001,261         0    240,203,941,461  2,285,404,265,546  0.00 B/s      0.00%    350,270,733,614         0    365,833,058,905
  Ethernet4        D  2,691,813,640,701  0.00 B/s      0.00%  2,044,188,179,972         0    918,880,245,693  2,181,295,289,532  0.00 B/s      0.00%    897,771,714,278         0    349,470,841,325
  Ethernet8        D  2,374,007,146,306  0.00 B/s      0.00%  2,390,883,192,821         0    300,393,297,279  1,627,669,035,123  0.00 B/s      0.00%    569,485,240,059         0     94,351,277,622
 Ethernet12        D  2,837,410,479,240  0.00 B/s      0.00%  1,288,679,352,877         0    417,034,819,423  2,355,856,598,490  0.00 B/s      0.00%    734,301,611,491         0    948,060,651,671
 Ethernet16        D  2,740,197,878,414  0.00 B/s      0.00%  2,621,988,106,679         0    777,300,884,914  3,703,464,652,903  0.00 B/s      0.00%    887,225,841,025         0    897,597,575,532
 Ethernet20        D  2,814,755,876,466  0.00 B/s      0.00%  2,090,398,383,057         0    201,661,521,758  2,217,451,593,841  0.00 B/s      0.00%    465,189,422,827         0    272,088,163,282
 Ethernet24        D                  0  0.00 B/s      0.00%                  0         0                  0                  0  0.00 B/s      0.00%                  0         0                  0
 Ethernet28        D  2,151,108,084,063  0.00 B/s      0.00%  2,117,863,285,888         0    101,705,702,270  3,001,875,678,191  0.00 B/s      0.00%    513,665,458,611         0    375,204,956,799
 Ethernet32        D  3,264,128,115,095  0.00 B/s      0.00%  2,624,579,657,640         0    938,695,826,347  2,237,579,139,102  0.00 B/s      0.00%    182,276,693,611         0    754,756,455,119
 Ethernet36        D  1,388,605,008,954  0.00 B/s      0.00%  1,032,370,865,099         0     67,305,471,435  2,815,768,604,754  0.00 B/s      0.00%    538,419,259,559         0    549,265,778,187
 Ethernet40        D  3,097,977,734,127  0.00 B/s      0.00%  1,468,197,728,764         0    823,433,939,818  3,508,559,915,050  0.00 B/s      0.00%    587,482,884,382         0  1,081,724,304,026
 Ethernet44        D  2,767,655,338,603  0.00 B/s      0.00%  1,498,689,796,523         0    528,258,661,030  2,802,804,323,061  0.00 B/s      0.00%    268,044,074,967         0    985,407,927,222
 Ethernet48        D  2,713,759,303,527  0.00 B/s      0.00%  1,575,788,134,426         0    789,860,308,069  3,607,712,273,047  0.00 B/s      0.00%    377,545,005,044         0  1,081,657,845,849
 Ethernet52        D  3,491,256,687,576  0.00 B/s      0.00%  2,455,430,724,492         0    649,704,836,349  2,034,750,688,109  0.00 B/s      0.00%    952,884,393,613         0    315,633,409,910
 Ethernet56        D  3,815,244,977,812  0.00 B/s      0.00%  2,206,045,440,664         0    833,159,166,405  3,160,122,412,616  0.00 B/s      0.00%    684,300,115,581         0    770,213,928,771
 Ethernet60        D  1,997,494,429,391  0.00 B/s      0.00%  1,864,667,304,178         0    291,911,265,790  1,861,622,066,234  0.00 B/s      0.00%  1,069,437,999,055         0    362,924,039,503
 Ethernet64        D  2,864,520,686,110  0.00 B/s      0.00%  1,987,087,532,827         0  1,016,464,124,343  2,350,321,984,601  0.00 B/s      0.00%    197,799,685,855         0    663,081,974,515
 Ethernet68        D  2,457,331,450,939  0.00 B/s      0.00%  1,086,411,965,452         0    276,075,216,177  2,365,961,700,054  0.00 B/s      0.00%    463,184,691,071         0    329,351,291,855
 Ethernet72        D  2,451,628,732,112  0.00 B/s      0.00%  2,895,197,231,278         0    891,062,939,606  2,179,839,493,977  0.00 B/s      0.00%    848,079,426,031         0  1,090,256,878,359
 Ethernet76        D  2,347,897,820,366  0.00 B/s      0.00%  2,041,630,789,394         0    514,724,719,408  2,358,488,156,406  0.00 B/s      0.00%    406,880,906,697         0    334,059,065,174
 Ethernet80        D  2,926,735,092,806  0.00 B/s      0.00%  1,122,260,750,722         0    826,166,565,945  1,693,901,621,155  0.00 B/s      0.00%    495,798,081,400         0    505,079,855,596
 Ethernet84        D  2,933,868,293,010  0.00 B/s      0.00%  1,290,644,152,020         0    445,964,963,165  2,384,252,965,964  0.00 B/s      0.00%    506,265,993,045         0    540,953,533,559
 Ethernet88        D  2,182,583,297,346  0.00 B/s      0.00%  1,273,888,687,805         0    936,159,697,358  1,747,388,128,703  0.00 B/s      0.00%  1,073,160,848,709         0    352,879,195,439
 Ethernet92        D  3,123,337,390,488  0.00 B/s      0.00%  1,279,978,561,846         0  1,090,904,621,041  2,167,755,463,604  0.00 B/s      0.00%    646,247,863,199         0    907,594,852,899
 Ethernet96        D  2,498,098,397,014  0.00 B/s      0.00%  1,024,608,760,869         0    506,107,608,933  1,427,913,220,971  0.00 B/s      0.00%    925,529,644,511         0    387,977,174,644
Ethernet100        D  2,151,588,404,300  0.00 B/s      0.00%  2,043,650,224,188         0    211,058,890,181  1,037,030,137,751  0.00 B/s      0.00%    407,582,623,069         0    350,397,748,572
Ethernet104        D  2,766,180,645,268  0.00 B/s      0.00%  1,247,823,628,279         0    936,134,528,782  1,032,169,932,563  0.00 B/s      0.00%    942,725,897,517         0     25,095,755,645
Ethernet108        D  2,709,040,331,509  0.00 B/s      0.00%  2,320,551,242,013         0    227,169,530,331  1,417,086,686,815  0.00 B/s      0.00%    373,890,037,460         0    332,120,030,583
Ethernet112        D  3,403,033,141,593  0.00 B/s      0.00%  1,649,128,632,588         0    920,922,100,015  2,466,182,849,097  0.00 B/s      0.00%    956,743,750,741         0    884,191,520,114
Ethernet116        D  2,528,901,607,694  0.00 B/s      0.00%  2,370,743,157,408         0  1,031,319,408,954  2,128,075,768,126  0.00 B/s      0.00%  1,092,823,285,644         0    470,131,113,822
Ethernet120        D  2,948,185,590,179  0.00 B/s      0.00%  2,049,815,555,275         0  1,053,405,440,221  1,970,717,268,003  0.00 B/s      0.00%    403,030,144,375         0    225,996,667,696
Ethernet124        D  3,291,319,936,510  0.00 B/s      0.00%  1,816,917,691,792         0    466,777,779,120  3,318,967,557,029  0.00 B/s      0.00%    178,949,930,691         0    187,875,449,549

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