Created SC2097 (markdown)

SC2097.md

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+## This assignment is only seen by the forked process.
+
+### Problematic code:
+
+    name=World cmd -m "Hello $name"
+
+### Correct code:
+
+    export name=World
+    cmd -m "Hello $name"
+
+To prevent setting the variable, this can also be done in a subshell:
+
+    (  
+       export name=World
+       cmd -m "Hello $name"
+    ) # 'name' does not leave this subshell
+
+### Rationale:
+
+In `name=World cmd "$name"`, `name=World` is passed in as part of the environment to `cmd` (i.e., in the `envp` parameter to [man 2 execve](http://linux.die.net/man/2/execve)).  This means that `cmd` and its children will see the parameter, but no other processes will.
+
+However, `"$name"` is not expanded by `cmd`. `"$name"` is expanded by the shell before `cmd` is ever executed, and thus it will not use the new value.
+
+The solution is to set the variable and export the variable first. If limited scope is desired, a `( subshell )` can be used.
+
+### Contraindications
+
+In the strange and fabricated scenarios where the script and a program uses a variable name for two different purposes, you can ignore this message. This is hard to conceive, since scripts should use lowercase variable names specifically to avoid collisions with the environment.