Re: Errors returned by System()function

From: Pedro Graca (hexkid_at_dodgeit.com)
Date: 11/18/04 

Date: 18 Nov 2004 22:17:05 GMT

["Followup-To:" header set to comp.lang.php.]
Randy Jackson wrote:
> I'm attempting to debug some code that uses the System function. When the
> function is called, it returns Error 1. Does anyone know what that error
> might be, or where I can find a list of error codes for the function?

The System() function returns a string!

If you mean it returns the string "Error 1", that means it executed the
specified command succesfully and /that/ command (whatever it was)
produced an output for which the last line was "Error 1".

If, on the other hand, you mean that the System() call returned false
(indicating a failure of the specified command) and that the second
parameter is 1 after the call, then it is the command you call within
the System() function that has the responsability for that.

For example ('echo $?' prints the exit status of the last command):

    php$ nocommand
    bash: nocommand: command not found
    php$ echo $?
    127

Seems that bash exits with a exit code of 1 when it can't find the
command

    php$ wget http://www.baddomain.net/index.html
    --21:57:02-- http://www.baddomain.net/index.html
               => `index.html.1'
    Resolving www.baddomainhere.net... failed: Host not found.
    php$ echo $?
    1

Seems that wget exits with a exit code of 1 when it can't resolve the
domain part of the URL

    php$ calc 78 + 3
            81
    php$ echo $?
    0

Seems that calc exits with a exit code of 0 when it works properly (as
do most (all?) other programs) 

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