Using Bash, but any shell is fine.

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73% accept rate
get unix encyclopedia – holms Feb 10 '11 at 3:14
Really? Closed? – slomojo Feb 10 '11 at 4:38
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closed as not constructive by nhinkle, KronoS, Sathya Feb 10 '11 at 4:31

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4 Answers

up vote 1 down vote accepted

As well as Arcege's list, learn how to use:

  • find
  • grep
  • tr
  • cut

Plus Bash built-ins like

  • while
  • for
  • if

Also learn about pipes, redirection, parameter expansion, brace expansion, readline, history and completion.

oh and...

  • man
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sed - file manipulation, e.g. sed -e '/<foo>/,/<\/foo>/{;s/bar/widget/;}' xyzzy.xml

awk - file manipulation, my favorite idiom is du -sk * | awk '{sum+=$1}END{print sum}'

less - paginator

tail -f - stream viewer, great for dozens of logs; tail -f logs/*.{log,err,out}

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To Arcege's list I'd add:

watch

as in

watch -d -n 'ls -al File*; wc -l File1'

(of course replace File*|File1 with whatever)

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Those commands that you listed "ls, cd, mv, cp, ..." are all just programs that happen to be installed on every unix and linux system. I often take a look around in the places where these programs reside like /bin, /sbin, /usr/bin, /usr/sbin. Then I use the man or info command to get more details on each of those commands in those directories. Use man man to get more details on the man command (press q to quit).

The ones I often use are grep, ssh, dd, nmap, ifconfig, route, and iptables (the firewall). I have by no means mastered iptables or grep. There are so many commands that each do different things and are each useful in their own way. It is difficult to pick the "most useful" ones. The ones that you consider most useful will depend on which programs best help with what you do most often.

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you could use grep every day for many many years, iptables however, you will rarely have to play with. – slomojo Feb 10 '11 at 4:26
@slomojo True grep defnetly stands out as one of the big ones that can be applied to just about anything. – James T Feb 10 '11 at 4:29
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