On AskUbuntu, I've seen a few commands around that look quite complicated, with lots of symbols in them. To get a better understanding of how these commands are built up, I'd like to know what the symbols stand for.

For example:

find ~/ -name *.c -exec sed -i "s/cybernetnews/cybernet/g" {} ;

or even more complicated:

echo -e "e[${i#*=}m$( x=${i%=*}; [ "${!x}" ] && echo "${!x}" || echo "$x" )e[m"

I understand very well that adding parameters as -c, --debug, have certain effects on the main commmand. The meanings of these are in almost all cases to be found in the man pages, so that's not really what I'm looking for.

Please, try in your answer to define what the symbols specifically do, instead of explaining the examples I gave. That could look like this:

" means 'argument': the main command uses anything within these symbols as its source

^ is used for ...

# is used for ...

Thanks in advance