Connect to wifi using commend line

You know, the ubuntu system in my Great Alienware is not healthy. Many functions are not working well, including the wifi connection. It is impossible to connect to a new wifi using the graphical interface. I will get error like:

I solved the connection issue using

Reference

1. 1. 1. Determine the name of the wifi. In many tutorials, they directly call their wifi “wlan0”. However, the name is different on my machine. Run the following command:
         
         (base) xiaoxu@chuan:~$ nmcli d DEVICE TYPE STATE CONNECTION wlp4s0 wifi disconnected -- enp5s0 ethernet unavailable -- lo loopback unmanaged --

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         (base) xiaoxu@chuan:~$ nmcli d DEVICE  TYPE      STATE         CONNECTION wlp4s0  wifi      disconnected  --         enp5s0  ethernet  unavailable   --         lo      loopback  unmanaged     --

         
         The name of my wifi is “wlp4s0”.
      2. List the wifi networks
         
         (base) xiaoxu@chuan:~$ nmcli d wifi list * SSID MODE CHAN RATE SIGNAL BARS SECURITY xfinitywifi Infra 6 54 Mbit/s 84 ▂▄▆█ HOME-CBE2 Infra 6 54 Mbit/s 82 ▂▄▆█ WPA1 WPA2 Neptune_EXT Infra 1 54 Mbit/s 77 ▂▄▆_ WPA1 WPA2 NETGEAR91 Infra 11 54 Mbit/s 60 ▂▄▆_ WPA2 Fios-TVB5U Infra 11 54 Mbit/s 54 ▂▄__ WPA2 2NXG7 Infra 6 54 Mbit/s 45 ▂▄__ WPA2 Zeus_EXT Infra 153 54 Mbit/s 45 ▂▄__ WPA1 WPA2 FiOS-A5O2K Infra 6 54 Mbit/s 40 ▂▄__ WPA2 nevetica Infra 6 54 Mbit/s 40 ▂▄__ WPA1 WPA2 -- Infra 6 54 Mbit/s 39 ▂▄__ WPA1 WPA2 Fios-TVB5U-5G Infra 161 54 Mbit/s 35 ▂▄__ WPA2 -- Infra 161 54 Mbit/s 35 ▂▄__ WPA2 -- Infra 1 54 Mbit/s 30 ▂___ WPA1 WPA2 DIRECT-PG-FireTV_3568 Infra 153 54 Mbit/s 30 ▂___ WPA2 -- Infra 1 54 Mbit/s 29 ▂___ WPA1 WPA2 802.1X -- Infra 1 54 Mbit/s 27 ▂___ OutOfService Infra 11 54 Mbit/s 27 ▂___ WPA2 802.1X -- Infra 161 54 Mbit/s 27 ▂___ WPA2 Axify Infra 11 54 Mbit/s 25 ▂___ WPA2 sergek5 Infra 36 54 Mbit/s 25 ▂___ WPA1 WPA2 xfinitywifi Infra 36 54 Mbit/s 24 ▂___ XFINITY Infra 36 54 Mbit/s 24 ▂___ WPA2 802.1X -- Infra 36 54 Mbit/s 24 ▂___ WPA1 WPA2 FiOS-A5O2K-5G Infra 161 54 Mbit/s 24 ▂___ WPA2 -- Infra 36 54 Mbit/s 22 ▂___ WPA1 WPA2 802.1X

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         (base) xiaoxu@chuan:~$ nmcli d wifi list *  SSID                   MODE   CHAN  RATE       SIGNAL  BARS  SECURITY            xfinitywifi            Infra  6     54 Mbit/s  84      ▂▄▆█                      HOME-CBE2              Infra  6     54 Mbit/s  82      ▂▄▆█  WPA1 WPA2            Neptune_EXT            Infra  1     54 Mbit/s  77      ▂▄▆_  WPA1 WPA2            NETGEAR91              Infra  11    54 Mbit/s  60      ▂▄▆_  WPA2                Fios-TVB5U             Infra  11    54 Mbit/s  54      ▂▄__  WPA2                2NXG7                  Infra  6     54 Mbit/s  45      ▂▄__  WPA2                Zeus_EXT               Infra  153   54 Mbit/s  45      ▂▄__  WPA1 WPA2            FiOS-A5O2K             Infra  6     54 Mbit/s  40      ▂▄__  WPA2                nevetica               Infra  6     54 Mbit/s  40      ▂▄__  WPA1 WPA2            --                     Infra  6     54 Mbit/s  39      ▂▄__  WPA1 WPA2            Fios-TVB5U-5G          Infra  161   54 Mbit/s  35      ▂▄__  WPA2                --                     Infra  161   54 Mbit/s  35      ▂▄__  WPA2                --                     Infra  1     54 Mbit/s  30      ▂___  WPA1 WPA2            DIRECT-PG-FireTV_3568  Infra  153   54 Mbit/s  30      ▂___  WPA2                --                     Infra  1     54 Mbit/s  29      ▂___  WPA1 WPA2 802.1X    --                     Infra  1     54 Mbit/s  27      ▂___                      OutOfService           Infra  11    54 Mbit/s  27      ▂___  WPA2 802.1X          --                     Infra  161   54 Mbit/s  27      ▂___  WPA2                Axify                  Infra  11    54 Mbit/s  25      ▂___  WPA2                sergek5                Infra  36    54 Mbit/s  25      ▂___  WPA1 WPA2            xfinitywifi            Infra  36    54 Mbit/s  24      ▂___                      XFINITY                Infra  36    54 Mbit/s  24      ▂___  WPA2 802.1X          --                     Infra  36    54 Mbit/s  24      ▂___  WPA1 WPA2            FiOS-A5O2K-5G          Infra  161   54 Mbit/s  24      ▂___  WPA2                --                     Infra  36    54 Mbit/s  22      ▂___  WPA1 WPA2 802.1X

      3. choose the wifi you want to connect to, and run the following commend:
         
         (base) xiaoxu@chuan:~$ nmcli d wifi connect ** password **

         1	(base) xiaoxu@chuan:~$ nmcli d wifi connect ** password **

      4.  Check whether the wifi is connected:
         
         (base) xiaoxu@chuan:~$ nmcli d DEVICE TYPE STATE CONNECTION wlp4s0 wifi connected NETGEAR91 1 enp5s0 ethernet unavailable -- lo loopback unmanaged --

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         (base) xiaoxu@chuan:~$ nmcli d DEVICE  TYPE      STATE        CONNECTION   wlp4s0  wifi      connected    NETGEAR91 1 enp5s0  ethernet  unavailable  --           lo      loopback  unmanaged    --

      5.  Notice: Actually in my desktop I still see an icon as no connection, but actually it is connected!