When you start working in Haiku, it is tempting to hit the repositories and download everything in sight. A lot of command-line files can be found there from the BeOS days. But you might want to check if you don’t already have them.
Take wget, for example: an excellent command-line utility that will reach out over the net and retrieve a file. You will find it on both Bebits and Haikuware, and if you download it you should install it into /boot/home/config/bin.
But wait a minute! Haiku already has its own wget, in /boot/system/bin. Now suppose you had both, which one would activate if you typed  wget in the Terminal? That is easy to find out, just type the following command:
echo $PATH
and it will spit out a list of directories all ending with „bin“ (for „binary“). Whenever you type a command in the Terminal, it will search those directories, in that exact order, for something to execute. On a typical system, /boot/home/config/bin always wins.
In fact, Haiku contains a lot of these command-line utilities that used to be separate downloads in BeOS. When I examined my bin directories I found duplicates of wget, top, reindex, clear and tput.  Now maybe the one in /boot/home/config/bin really is more up-to-date, in which case you can just leave it alone. But will you remember to check after Haiku next receives an update? And there is a real possibility that you are using an out-of-date version.
So before you download and install anything for the Haiku command line, just open a Terminal and type that command to see if it isn’t there already.