iperf write file

devce:~ # iperf3 -s -F iperf.txt
-----------------------------------------------------------
Server listening on 5201
-----------------------------------------------------------
Accepted connection from 192.168.10.2, port 39060
[  5] local 192.168.10.4 port 5201 connected to 192.168.10.2 port 39062
[ ID] Interval           Transfer     Bitrate
[  5]   0.00-1.01   sec  28.2 MBytes   235 Mbits/sec
[  5]   1.01-2.00   sec  28.6 MBytes   241 Mbits/sec
[  5]   2.00-3.01   sec  28.8 MBytes   241 Mbits/sec
[  5]   3.01-4.01   sec  28.5 MBytes   239 Mbits/sec
[  5]   4.01-5.01   sec  28.4 MBytes   237 Mbits/sec
[  5]   5.01-6.00   sec  28.4 MBytes   239 Mbits/sec
[  5]   6.00-7.01   sec  28.8 MBytes   240 Mbits/sec
[  5]   7.01-8.01   sec  28.5 MBytes   240 Mbits/sec
[  5]   8.01-9.14   sec  16.4 MBytes   121 Mbits/sec
[  5]   9.14-10.00  sec  21.1 MBytes   206 Mbits/sec
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate
        Sent  266 MByte /  266 MByte (100%) of iperf.txt
[  5]   0.00-10.00  sec   266 MBytes   223 Mbits/sec                  receiver