How to solve the problem?
Look carefully at what you typed, hint: ficonfig isn't a command. Bash (and virtually every programming language out there) is very particular about syntax (correct command). Ex: pin wouldn't work but ping would. Try again because you were close to the right answer.
Short answer is, you spelled them wrong.
ok,i find it...but command dhclient really doesn't work...
What exactly are you trying to use this command for? There may be flags/switches you can give to get the desired output.
You may want to take a look at this.