Permission problem running a compiled C++ program

[palmerac]

I boot with Knoppix 3.7 and am still learning Linux. I need to clone a hard drive with lots of errors (dd can't handle it). I have obtained the source for GNU ddrescue (not to be confused with dd_rescue, written by Kurt Garloff), written in C++ by Antonio Diaz. http://www.gnu.org/software/ddrescue/ddrescue.html

I had no problems unzipping and untarring the source files, and I was able to './configure' and then 'make' it (in the same directory on my USB flash drive where the source code is stored).

But now I'm having trouble getting ddrescue to run. If I run it from 'Konsole' terminal with this invocation

ddrescue /dev/hdc /dev/hdb testlog

I get the following error: "ddrescue: cannot open input file: permission denied". I think this is because accessing a full drive like hdb or hdc (rather than a partition like hdb1 or hdc2) can only be done from Root.

But when I launch a 'Terminal as Root' window (logging in as root with a password that I set myself) and navigate (cd) to the correct folder with the compiled folder, I am unable to invoke ddrescue...

root@ttyp1[ddrescue-1.0]# ddrescue /dev/hdc /dev/hdb testlog
bash: ddrescue: command not found

What am I doing wrong? Is there another shell that I should be using?

[angor]

Root probably (and wisely!) does not have the current directory (.) in her PATH. Try ./ddrescue (that's dot-slash)

[palmerac]

THANKS!! Using ./ddrescue worked just fine, although I don't really understand why...

I thought that the . (dot) specifies current directory, so ./ddrescue is telling the system to run ddrescue from a subdirectory of the current directory that I'm in?

[angor]

Yes, "." does mean the current directory. When you use a command that is not in a directory mentioned in PATH
(type "echo $PATH" to see what's in there), then everything you type up to the last "/" is the path to the executable,
the rest is the name of the executable itself. Try playing with the commands "basename" and "dirname".

HTH