Problem installing on Raspberry Pi3.. No such directory
Fred Kerfwappie
John Maxwell
> Hello and thank you,
>
> Please help. I'm trying to install and running into a problem. When I
> try
> to get to the directory "gqrx" ( cd /gqrx) , it says that the
> directory
A short introduction to directories in Linux (this also applies to other
flavors of Unix, and, with some slight modifications, to Windows as
well, although Microsoft do their best to obscure it.)
Linux directories are arranged in a tree-like structure, only the tree
is upside down; it's narrow at the top, and branches out as you go down
from the top.
The top-most directory is called the "root", and is referred to as /
The second part of the "cd" command is the name of the directory you
want to go to. There are two ways to write a directory name. The first,
which you were using, is to use an "absolute" location, which you do by
starting at the root ("/"), and adding the names of any sub-directories
that lay between the root and your ultimate destination, separating the
sub-directory names with / characters.
So, by saying "cd /gqrx", you were saying "I want to go to the directory
named gqrx, located immediately under the root directory". And it's
likely that there is no such directory. (There's no fundamental reason
that there _couldn't_ be such a directory, but it would be
unconventional, and provide no benefit).
Linux treats directories like locations. You're always "located"
somewhere in that tree. Your location is called the "current directory."
The other way to specify a directory name is "relative", which means
"relative to your current location." You do this by simply not using a
leading / character. This means that the name starts from your current
location, not from the root of the directory tree.
So, the command I gave you above, "cd gqrx", means "go to the directory
named gqrx directly under the current directory." If you were currently
located in the root directory, the commands "cd /gqrx" and "cd gqrx"
would have exactly the same effect. If you're not in the root directory,
they have different effects.
The final bit of information that you need to understand what's going on
here is this: After you log into Linux, your current directory (your
current "location") is NOT the root directory. It's what's called your
"home" directory, and is different from user to user.
By convention, the home directories are located under /home (so, they're
underneath the directory named "home", which is directly under the root
directory, "/"), and have the same name as the user's name.
So, if a user named "foo" logs onto the machine, his current directory
will be his home directory, which will be "/home/foo". Likewise, when
the user "pi" logs onto the machine, he will find himself in _his_ home
directory, "/home/pi".
I'm guessing that you installed gqrx under your home directory (which is
not certain, but is a reasonable guess), and that you're trying to cd
into its directory immediately after logging in.
(A useful thing to know when wandering around the directory tree is that
the command "cd", with no directory name, will take you home; that is,
back to your home directory.)
Hope this helps some.
-John
--
John Maxwell KB3VLL jm...@jmaxhome.com
"Israel is slightly smaller than New Jersey. Moses in effect led the
tribes of Israel out of the District of Columbia, parted Chesapeake
Bay near Annapolis, and wandered for forty years in Delaware."
-- P.J. O'Rourke
Robin Gape
Fred,
there are folk on this list all the way from absolute tyros, to
some who have been dealing with computers for 50 years, and first
dealt with Unix over 30 years ago. You get the idea of the wide
range of knowledge and skills. Unless you tell us directly, the
list mavens have to make a guess at where you stand, and hope to
be neither patronising nor over-your-head.
That said, are you trying to install on Ubuntu, or are you trying
to install on a Raspberry Pi, or doing something else? What set of
instructions are you trying to follow? [Installation under Ubuntu
or on a Raspberry Pi should be comparatively straightforward if
using the instructions to be found at http://gqrx.dk/.]
As John said, the instructions probably meant, and should have
read, ./gqrx. In the world of Linux (and Windows, and
OS/X) a tiny dot makes a big difference! The dot refers to the
current working directory. If one types pwd, then the
result is where in the directory tree actions will take place.
(The command line is unforgiving of poor eyesight or sloppy
typing!)
As a newcomer, you may have noticed that a lot of introductory material that a search engine will turn up is:
• old (not necessarily a bad thing for stuff that hasn't changed—but how does a newcomer know?)
• out of date (definitely bad, since it can be quite misleading, especially for a newcomer)
• focussed on the command line
• written without empathy for the beginner
• simply gnarly
All that said, there is useful introductory material if one doesn't mind having to sift through lots of stuff. You could probably do a lot worse than start at https://www.lifewire.com/beginners-guide-to-linux-4090233.
This introduction to Ubuntu is pretty up-to-date, but is less
relevant if you're not using Ubuntu:
https://www.makeuseof.com/tag/ubuntu-an-absolute-beginners-guide/.
HTH,
Robin, G8DQX
Fred Kerfwappie
Thank you John and Robin for your time. Sorry, it took so long to get back to you. I have been busy at work and haven't been able to play with my toys. I am slowly learning Linux and very much appreciate the patient tutorial. I am running on a Raspberry Pi. I did manage to get GQRX installed and running with the help of a few videos. I am now having difficulty with the settings for my particular SDR. I am using the RTL_SDR in the blue aluminium case with the dolphin on it. I know that it should have a brand name somewhere, but who knows? I am starting from the desktop environment. It gives me an error message about the configuration settings not being right and offers me an opportunity to change the settings. I found them at one time and did get the HF to work. Should have written it down. Like you said, there is so much to sift through. Thanks again.
