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When, I try to cat the speed file, in /sys/class/net I get the following error

$ cat /sys/class/net/wlan0/speed 
cat: /sys/class/net/wlan0/speed: Invalid argument #throws error

Whereas, for eth0 it shows

$ cat /sys/class/net/eth0/speed

Can I know the reason for the error for wlan alone. Also the duplex is unkown for wlan0 but the carrier is set to 1?

marked as duplicate by Archemar, GAD3R, sam, don_crissti, slm linux Dec 27 '16 at 16:48

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You can use all of these commands (I recommend ethtool)

dmesg | grep <interface>


ethtool <interface>


Look at the output of iwconfig <interface>.

  • yeah. It's working thanks. Can I know from which file does iwconfig calculates – Arunagiriswaran Ezhilan Dec 27 '16 at 15:33

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