Linux 查詢網路卡連線速度

用 ifconfig 查網路卡的代號 (如下 ens18)
$ ifconfig
ens18: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.0.213  netmask 255.255.255.0  broadcast 192.168.0.255
        inet6 fe80::805d:2cff:fe83:be86  prefixlen 64  scopeid 0x20<link>
        ether 82:5d:2c:83:be:86  txqueuelen 1000  (Ethernet)
        RX packets 180421  bytes 28681530 (27.3 MiB)
        RX errors 0  dropped 9  overruns 0  frame 0
        TX packets 102287  bytes 156632224 (149.3 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0


$ cat /sys/class/net/ens18/speed
1000   <!--1000MB/s 的速度

若系統中有安裝 ethtool 時：

$ ethtool ens18
Settings for ens18:
        Supported ports: [  ]
        Supported link modes:   Not reported
        Supported pause frame use: No
        Supports auto-negotiation: No
        Supported FEC modes: Not reported
        Advertised link modes:  Not reported
        Advertised pause frame use: No
        Advertised auto-negotiation: No
        Advertised FEC modes: Not reported
        Speed: 1000Mb/s
        Duplex: Full
        Auto-negotiation: off
        Port: Other
        PHYAD: 0
        Transceiver: internal
netlink error: Operation not permitted
        Link detected: yes

另外，在 /sys/class/net/ens18/statistics/ 目錄底下，也有該網卡的各項流量資料；

$ ls /sys/class/net/ens18/statistics/
collisions     rx_crc_errors   rx_frame_errors   rx_over_errors     tx_carrier_errors  tx_fifo_errors
multicast      rx_dropped      rx_length_errors  rx_packets         tx_compressed      tx_heartbeat_errors
rx_bytes       rx_errors       rx_missed_errors  tx_aborted_errors  tx_dropped         tx_packets
rx_compressed  rx_fifo_errors  rx_nohandler      tx_bytes           tx_errors          tx_window_errors


網卡傳出的 bytes 數量
$ cat /sys/class/net/ens18/statistics/tx_bytes
156676775

網卡接收的 bytes 數量
$ cat /sys/class/net/ens18/statistics/rx_bytes
28836537