Re: Testing for a value not sent to a shell script

[John McKee <jmmckee@xxxxxxxxxxxxxx>]

I was uncler.  I was referring to Qshell.

This started out simple.  I want to run an sftp to generate a lit of 
files on remote server.  Then, use n sftp to get the file, one at a 
time.  In MOST
cases, there will only be one file to retrieve.  However, the site has a
history of going down.  Thus, with a job submitted to batch, the site could be
down or not.

The file or files would subsequently need to be copied from a stream file to a
database file.  CPYFRMIMPF seems to work nice for this.  Finally, an RPG
program reads that files and writes to the actual database file.

Obviously, I don't actually need to check for a missing parameter.  
Maybe it is
not even a good idea.  Better approach might be to have two functions in the
script, one to get the list and the second to get the files.

something like this:
for i in `get_file_list`
do
   get_file $i
   system(CPYFRMIMPF...........)
done

And the CL that calls this QSH script would then invoke the RPG program to
finish up.

My initial thought was if a function was not supplied, then it would 
return the
lit of files.  But, it is just as easy to use two functions, and likely 
clearer
as well.


I think I made the issue more complicated than it needed to be.

But, simple question is this:

I thought there was a $something that returned the number of arguments 
supplied.
I can't remember what the character following the $ is that had the argument
count.

If I needed to write a script that needed to default to something if a single
argument was omitted, what is that function?  For instance cal does current
month and cal with 2009 does the given year.

Really not an issue, after more thought.  I mislaid my K&P book years ago that
detailed the various values.

John McKee


Quoting Scott Klement <midrange-l@xxxxxxxxxxxxxxxx>:

> Hi John,
>
> > I am drawing a blank here.
> > How do I test for the absence of of a parameter in a shell script?
>
> I'm assuming you by "shell script" you mean either QShell or Bourne
> shell.  If that's wrong, please tell me so.
>
> It depends on what you mean by "absence".  Consider the following
> command-line that runs a script of mine:
>
>   runxfer.sh -u klemscot -p bigboy sftp.klements.com
>
> If I changed it to look as follows, what would be "absent"?
>
>   runxfer.sh -u klemscot sftp.klements.com
>
> Would I say that the 3rd and 4th parameters weren't passed?  Because,
> technically, the 3rd parameter WAS passed... it just isn't -p anymore.
> So it's really a hard question to answer.  It really depends on the
> paradigm in which you wrote your script.
>
> how about if I did this:
>
>   runxfer.sh -u klemscot -p "" sftp.klements.com
>
> Now I have the same number of parameters as my original example, but one
> of them is an empty string.  Does that count as being passed or not?
>
> So, really, the first thing you need to decide...  how are you handlign
> parameters?  Are you using option flags with values?  Or is it purely
> positional?
>
> Then you need to decide what is considered "absence"?  If a string is
> passed, but is blank, is that considered absent?
>
> Sorry.  I hate complicating things -- but I want to make sure I'm
> answering the right question.
> --
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