## What does 2>&1 | tee mean?

I read the answer by @grg to question “brew formula” installation logs:

brew install 2>&1 | tee install.log

So where exactly this install.log file is going to end up and what exactly the `2>&1 | tee` part of the command mean?

## What does 2>&1 | tee mean?

I read the answer by @grg to question “brew formula” installation logs:

brew install 2>&1 | tee install.log

So where exactly this install.log file is going to end up and what exactly the `2>&1 | tee` part of the command mean?

## What does 2>&1 means in crontab commands?

I’ve seen many crontab commands written this way:

``*/5 * * * * ~/script.sh >/dev/null 2>&1 ``

Can someone explain what is the exact meaning of `2>&1` in this script?

## Find the amount of subgroups of order \$3\$ and \$21\$ in non-cyclic abelian group of order \$63\$

Find the amount of subgroups of order $$3$$ and $$21$$ in non-cyclic abelian group of order $$63$$.

In first case I found the amount of elements that have order $$3$$ – there are $$8$$ of them, in second case there are $$48$$ elements of order $$21$$. How do I connect these values with the amount of subgroups now?