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How to force Network Manager in Ubuntu to rescan wireless connections?

After closing my laptop, network manager does not see new wireless connections. Is there any bash command to force rescan? sudo service network-manager restart does not help.

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7 Answers 7

Reset to default
28 
sudo iwlist interface scan

Where interface is the name of your wireless card, e. g. wlan0

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4
  • use sudo ifconfig to find out the name of the "interface"
    – Bhikkhu Subhuti
    Aug 26, 2016 at 10:58
  • Do you really need to use sudo for this?
    – Morten
    Jul 12, 2017 at 8:04
  • @Morten: Yes, we do need sudo. "Triggering scanning is a privileged operation (root only) and normal users can only read left-over scan results." (man iwlist)
    – Falko
    Aug 8, 2018 at 9:26
  • This answer does not use NetworkManager. See @Davide's answer which does.
    – Hugh W
    Sep 24, 2020 at 16:37
29

Try 

nmcli device wifi rescan

and

nmcli device wifi list

to see available networks

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2
  • 3
    Best answer. Without using sudo.
    – Khurshid Alam
    Jul 5, 2017 at 6:17
  • 3
    This should be the accetpted answer. It is, after all, the "command-line tool for controlling NetworkManager". It gives a nice graphical command-line output if you specify list (or no argument at all).
    – Mike S
    Oct 31, 2017 at 12:06
2

In Ubuntu 16.04 and newer, restarting NetworkManager with sytemctl works (at least after scanning the networks manually with iwlist):

# Find the name of the network interface, e.g. wlan0 or wlp3s0
ip addr show      

# Scan for WLAN networks (replace wlan0 by the correct interface)
sudo iwlist wlan0 scan

# Restart Ubuntu’s Network Manager so it reloads the Access Point list
sudo systemctl restart NetworkManager
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2

I have too low reputation to elaborate under Davide's answer so I decided to add a new answer. Create a file /usr/share/applications/rescan.desktop with the following contents to be able to easily launch a rescan through the dashboard:

[Desktop Entry]
Name=Rescan wifi
Type=Application
Exec=/usr/bin/nmcli device wifi rescan
Terminal=false
Icon=network-wireless
NoDisplay=false
Categories=Network;System
Name[en]=Rescan wifi
Name[en_US]=Rescan wifi
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1

sudo /etc/init.d/networking restart should work...

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1

Simply deactivating and reactivating your wireless module would be a workaround.

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  • 1
    -1. Though this naively seems like a decent solution, it eventually led me to hard-block my network card for the weekend.
    – Abhishek Divekar
    Feb 12, 2017 at 18:28
  • I do this by enabling and disabling the airplace mode using my laptop keyboard's function key shortcut
    – Spikatrix
    Jan 25, 2020 at 3:00
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The checked answer is incorrect for most situations. Only nmcli controls NM.

The first thing to do is to check for NM's radio status:

$ nmcli r

This will let you know if the wifi radio is enabled.

If not, then:

$ nmcli r wifi on

You can then confirm the result:

$ sudo nmcli device wifi list
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