Verifiying commands entered

Matthias Koll matt.koll at
Thu Oct 19 13:57:17 PDT 2006

Ken Moffat wrote:
> I too would expect to see the updated time, but I've never looked
> at the data and time here, so I might be missing something.
>  First test: look at your command history ('history', or just
> up-arrow) - did you key the command correctly ?
Yes, but.....
What I only found out now is that simple line wrapping is not working. I 
need to place the continuation character at the end of the line.
And also should probably break up sensibly. I guess you can call this a 
typical Newbie error.

>  Second test: diff{,.tmp}  - are they different ?

Now they are, orig file is 180686, new in file is 180682
Diff tells me the following:
$lfs: diff{,.orig}
<        $(SHELL) -c true ../../gcc/include \
 >        $(SHELL) ./ ../../gcc/include \

And that looks good enough to me.
Would it be an idea to put the diff command for verification in the book?
Assuming that this is the output expected?

>> I am still trying to work out why this part of the command did not work,
>> as I did not get any message indicating an unsuccesful execution.
>  Probably, you mis-keyed something (again, check the history if
> still available).  I'm glad the check caught the problem.
Not miskeyed but broke at the wrong time with no continuation character:
> That's difficult - some commands will report errors, others will
> quietly end with a non-zero status [ echo $?  to check that ] and
> some tend not to tell you - I'm thinking particularly of sed: error
> messages from it mean syntax errors or missing files, they don't
> tell you whether or not anything was changed.  So, it's easy to
> mistype a sed command and either change nothing, or change the wrong
> thing.  If you know what a sed is supposed to do, in early chapter 5
> diff will tell you what got changed (later on, we can do in-place
> seds, so diff won't help you wiht those).
> Ken
echo §? is already another step on my learning curve. Thanks.

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