How do I check to see if an environment variable exists?

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How do I check to see if an environment variable exists?

Pi Digital via use-livecode
Hi All,

Looking to see how I check to see if my standalone was launch via command line with a parameter?

I know that when it’s launched via command line with a parameter in windows, I will see a $0 (Name of executable) and $1 for the parameter.

Since this is a dual launch able app, double click and command line with parameter I have the following in the main stack:

on openStack

if exists($1) then

put $1 into pState

put "prod" into pMode

runBuildAndPush pState, pMode

end if

end openStack


However, the exists($1) never returns true, even when it should. Which leads to to believe that’s not what I want to use.

How would I test to see if the $1 variable exists?

TIA,

Steve MacLean



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Re: How do I check to see if an environment variable exists?

Pi Digital via use-livecode
$# tells you how many parameters there are for a script. Perhaps if $# > 0 then... instead might work (I’ve not tried that). You might find using environment() potentially helps as well. The Dictionary has the details. If neither of those options work let me know. I have another way you could tackle the issue.

- Bob Hall

> On Nov 23, 2018, at 5:27 PM, Stephen MacLean via use-livecode <[hidden email]> wrote:
>
> However, the exists($1) never returns true, even when it should. Which leads to to believe that’s not what I want to use.
>
> How would I test to see if the $1 variable exists?

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Re: How do I check to see if an environment variable exists?

Pi Digital via use-livecode
> How would I test to see if the $1 variable exists?

I don't check for existence, I only check whether it's empty.
--
Jacqueline Landman Gay | [hidden email]
HyperActive Software | http://www.hyperactivesw.com
On November 24, 2018 8:04:50 AM bob--- via use-livecode
<[hidden email]> wrote:

> $# tells you how many parameters there are for a script. Perhaps if $# > 0
> then... instead might work (I’ve not tried that). You might find using
> environment() potentially helps as well. The Dictionary has the details. If
> neither of those options work let me know. I have another way you could
> tackle the issue.
>
> - Bob Hall
>
>> On Nov 23, 2018, at 5:27 PM, Stephen MacLean via use-livecode
>> <[hidden email]> wrote:
>>
>> However, the exists($1) never returns true, even when it should. Which
>> leads to to believe that’s not what I want to use.
>>
>> How would I test to see if the $1 variable exists?
>
> _______________________________________________
> use-livecode mailing list
> [hidden email]
> Please visit this url to subscribe, unsubscribe and manage your
> subscription preferences:
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Re: How do I check to see if an environment variable exists?

Pi Digital via use-livecode
Thanks all!

I am basically doing what Jacqueline does and check to see if empty and then verify against a list of switches.

It does seem strange that we can’t check for the existence of a variable, but this works.

Thanks,

Steve MacLean

> On Nov 24, 2018, at 11:35 AM, J. Landman Gay via use-livecode <[hidden email]> wrote:
>
>> How would I test to see if the $1 variable exists?
>
> I don't check for existence, I only check whether it's empty.
> --
> Jacqueline Landman Gay | [hidden email]
> HyperActive Software | http://www.hyperactivesw.com
> On November 24, 2018 8:04:50 AM bob--- via use-livecode <[hidden email]> wrote:
>
>> $# tells you how many parameters there are for a script. Perhaps if $# > 0 then... instead might work (I’ve not tried that). You might find using environment() potentially helps as well. The Dictionary has the details. If neither of those options work let me know. I have another way you could tackle the issue.
>>
>> - Bob Hall
>>
>>> On Nov 23, 2018, at 5:27 PM, Stephen MacLean via use-livecode <[hidden email]> wrote:
>>>
>>> However, the exists($1) never returns true, even when it should. Which leads to to believe that’s not what I want to use.
>>>
>>> How would I test to see if the $1 variable exists?
>>
>> _______________________________________________
>> use-livecode mailing list
>> [hidden email]
>> Please visit this url to subscribe, unsubscribe and manage your subscription preferences:
>> http://lists.runrev.com/mailman/listinfo/use-livecode
>
>
>
>
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Re: How do I check to see if an environment variable exists?

Pi Digital via use-livecode
In reply to this post by Pi Digital via use-livecode
Stephen MacLean wrote:

 > Looking to see how I check to see if my standalone was launch via
 > command line with a parameter?
 >
 > I know that when it’s launched via command line with a parameter in
 > windows, I will see a $0 (Name of executable) and $1 for the
 > parameter.
...
 > How would I test to see if the $1 variable exists?

    if "$1 is among the lines of the globalNames then ...

But that won't tell you if your app is running from the command line.

If the user double-clicks a document associated with your app, the OS
will pass the path to the document to the app in $1.

To determine if an app is running facelessly from the command line
(assuming you include -ui as an option with the command to bypass
loading the GUI), see the environment function:

    if the environment is "command line" then ...

--
  Richard Gaskin
  Fourth World Systems
  Software Design and Development for the Desktop, Mobile, and the Web
  ____________________________________________________________________
  [hidden email]                http://www.FourthWorld.com

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