I attempted to use the following command in my terminal (Ubuntu 18.04)

ifconfig grep ether

and received the following output message:

SIOCSIFMTU: Operation not permitted

So I was going to ask why and what this means, but knowing me I will post a question for every line output I don't understand, everytime I am on my Linux system, and it wont be long before people here start to find me really annoying.

So what I am hoping for, is a command that I can call from within the terminal window that will return documentation relevant to the last line of output received, if this isn't possible then I will just have to search in my browser window, but because there are so many different ways to achieve the same result, and usually only one of them applies to the installation I am working from, it would save a lot of time if I could look up and display documentation relevant that is already on my local machine.


I just thought of another means of potentially achieving the same result, I open the onion browser via the terminal, is there a means for which I can append a target http address and a list of search terms to be executed upon opening a new tab in my browser via the terminal, a portion of these search terms being the output that I need to information on?

ie a command that:

  • opens a new tab on the browser I opened when I first opened the terminal
  • inserts a target address for the search engine i wish to use
  • when this search engine is ready to receive input, inserts search terms, which include the version of Ubuntu I am running, machine specifications, and the output i desire to learn more about, in this case, "SIOCSIFMTU: Operation not permitted".

1 Answer 1


Your command has wrong syntax. Current command ifconfig grep ether means that you call ifconfig with two arguments - grep and ether. Both are unknown to ifconfig util (see man ifconfig for details).

So you forget two moments:

  1. add pipe symbol (|)
  2. ignore case while greping to get Ethernet in the search result.

The correct one would be

ifconfig | grep Ether


ifconfig | grep -i ether

Here -i (or long variant --ignore-case) means

Ignore case distinctions, so that characters that differ only in case match each other.

For details see man grep.

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