AE environment variable prefixes

AE environment prefixes are appended to the front of an environment key name, providing instructions to the AE runtime system. The prefixes are processed and removed, leaving only the actual key name. Multiple prefixes can be used, but must appear in a definite order that is determined by order of precedence.

Precedence Level 0

When present, these prefixes restrict the environment variable to either the host or the S-Blade (SPU).

NZAE_HOST_ONLY_
NZAE_SPU_ONLY_

Precedence Level 1

When present, this prefix instructs the AE runtime not to perform variable (%{ }) or shared library name substitution (%[ ]).

NZAE_NO_SUBSTITUTE_ :

Precedence Level 2

These prefixes indicate that the value is to be appended or prepended to an existing environment value. If the key is not defined, then it is created with this value. AE runtime first searches for an AE environment key and then a Linux OS environment key to find an existing value.

NZAE_APPEND_
NZAE_PREPEND_

The following prefixes are used to include files containing AE environment variables, as described in the section AE Environment Variable Include Files. NZAE_INCLUDE_BEFORE and NZAE_INCLUDE_AFTER_ are allowed in include files but do not affect processing order. The prefixes must appear in precedence order, from low to high. Only one entry from each precedence level can be used with a key. For more information, see Order of variable parsing.

NZAE_INCLUDE_;
NZAE_INCLUDE_BEFORE_;
NZAE_INCLUDE_AFTER_;

The following example demonstrates an existing key that is used only on the S-Blade called MY_RANDOM_ASCII_CHARS. Variable or shared library substitution is not desirable, but might occur since "%[" and "%{" sequences are possible. If an environment value already exists for this key, the value should be appended after it:

NZAE_SPU_ONLY_NZAE_NO_SUBSTITUTE_NZAE_APPEND_MY_RANDOM_ASCII_CHARS="a789%[ [[%%%
{}}}89 90"

This example demonstrates prefix usage in its most general form, although it is likely more complex than most applications require.