How do I grab variables specified in a data file and use them in the script?

billy72j · 12-23-2010, 06:23 AM

I have a script which uses a Menu file (containing several different Menus). I start out with

Code:

Menu=Main

and grep my VRMenuData file for

Code:

$Menu\:code:$txtring

, where txtring contains the value entered from the keyboard, and cut that line for the code I want executed. So my data looks like:

Quote:

Main:code:1:declare Menu=Download
Main:code:2:soffice -calc VRSched.ods
Main:code:3:echo Load Refresh Menu here

My code acting on the data looks like:

Code:

`grep $Menu\:code:$txtring VRMenuData | cut -d: -f4`

When I chose options 1 thru 3, that executes with no problem (Menu=Download does not work). The program sees into field four, but field four is not able to see outside itself. For instance:

Code:

Download:chan:
Download:pitm:1:echo $numpi\. Return to Main Menu
Download:pitm:2:  
Download:pitm:3:  
Download:pitm:4:echo Enter Menu number (q quits):

Above is more of the VRMenuData file. The

Code:

Download:chan

is used to generate a numbered list of channels. It could be four or 40. Whatever the number is, I want the next line to read, for example, 32. Return to Main Menu.

Code:

num

is the variable in the script I use to number the list of channels. The number following Download: pitm: is numpi, which should be added to num. How do I take

Code:

Download:pitm:1:echo $numpi\. Return to Main Menu

from my VRMenuData file and generate

Code:

32. Return to Main Menu

?

Code:

$ declare -p Menu
declare -- Menu="Download"
$ declare -p numpi
declare -- numpi="1"
$ grep $Menu\:pitm:$numpi VRMenuData | cut -d: -f4
echo $numpi. Return to Main Menu

grail · 12-23-2010, 06:45 AM

Well I would be lying if I didn't say I am struggling to understand exactly, but let's see if i am on the right track:

In the file VRMenuData is (for example):

Code:

Download:chan:
Download:pitm:1:echo $numpi\. Return to Main Menu
Download:pitm:2:  
Download:pitm:3:  
Download:pitm:4:echo Enter Menu number (q quits):

You then have the following variables set in a script:

Code:

Menu="Download"
numpi="1"

Then you submit the following grep and cut using the above variables:

Code:

grep $Menu\:pitm:$numpi VRMenuData | cut -d: -f4

This then correctly returns:

Code:

echo $numpi\. Return to Main Menu

Assuming all the above is correct?? You would like the result of the grep to be executed??

Well firstly I have no idea how 32 would suddenly come into it seeing numpi is equal to 1, but this would give the output with this value:

Code:

eval $(grep $Menu\:pitm:$numpi VRMenuData | cut -d: -f4)

I would urge you to strongly consider if this is what you need as eval can have a lot of complications.

If I am completely off track, please advise?

billy72j · 12-23-2010, 09:37 AM

The Download:chan: line triggers a process in the script that goes to my channel format file and loads the list of channels in the Menu list I have as an array. This list can vary in length. So if I have, for example, 31 channels
1. Fox News
2. Fox Sports
3. Vox
.
.
.
30. CNN
31. Discovery
Well, the next line I want is in my VRMenuData file which triggers on Download: pitm:1, where Menu=Download and numpi=1 (':' and 'p' without a space in between gives an unwanted emoticon, hence the space between them). However, I want that listed as item 32 on my Menu list, so they know how to get back to the Main Menu. After that, numpi gets incremented to insert two blank lines and then when numpi is four, it will add to the Menu list

Code:

Enter Menu number (q quits):

I had success with the following in a terminal window:

Code:

 $ declare -p num
declare -- num="5"
$ declare -p numpi
declare -- numpi="1"
$ echo `expr $num + $numpi + 1`. Return to Main Menu
7. Return to Main Menu

I tried putting that into my VRMenuData file and it seems to be working. When it executed

Code:

pval=`eval $(grep $Menu\:pitm:$numpi VRMenuData | cut -d: -f4)`
echo $pval

What came out was

Code:

7. Return to Main Menu

Is there a good way to have that added from within the script? This would help keep the VRMenuData file simpler.

Thanks for your help, Grail.

grail · 12-23-2010, 10:18 AM

Have you looked at the select statement? It can generate all the numbers for the inputted data and then acts on the number returned once entered.

I would again warn about eval giving sometimes unreliable results. Now you have added more process substitution and expr ... just a caution.