Make

Detecting OS in makefile

From [OS detecting makefile][http://stackoverflow.com/a/714135/306935]

UNAME := $(shell uname)

ifeq ($(UNAME), Linux)
# do something Linux-y
endif
ifeq ($(UNAME), Darwin)
# do something Solaris-y
endif
ifeq ($(UNAME), Solaris)
# do something Solaris-y
endif

Variable assignment

From Stack Overflow

Normal setting of a variable – values within it are recursively expanded when the variable is used, not when it’s declared
```
VARIABLE = value
```
Setting of a variable with simple expansion of the values inside – values within it are expanded at declaration time.
```
VARIABLE := value
```
Setting of a variable only if it doesn’t have a value
```
VARIABLE ?= value
```
Appending the supplied value to the existing value
```
VARIABLE += value
```