Command return codes?

[ridera]

Can anyone provide us with a little info on the command return codes?

e.g., using php/shell

Code: Select all

exec("convert-path $map_fpfile -colors 100 -quality 75  -resize $width x $height  $saved_fpfile", $array, $var);

$array is empty and $var is assigned a number.

When the command works, $var= 1; when it doesn't, $var= 127 for one type of forced error.

I can't find a list of error codes anywhere.

Is "1" the proper return for a good execution and anything orther than "1" not?

Or, should maybe "0" be the proper return for a good executon and the "1" is indicating some is wrong even though the command seems to be working?