makefile notes

makefile-notes.md

Table of Contents

• Automatic Varaiables
• Implicit Rules and Variables
• Include Path
• Substituion
• Environment Variables

Automatic Variables

• https://www.gnu.org/software/make/manual/html_node/Automatic-Variables.html

Implicit Rules and Variables

Use make --print-data-base | less to view impicit rules

Include Path

my_include_path = a b c
my_path = $(addprefix -I,$(my_include_path))

• my_path is -Ia -Ib -Ic

Substitution

a = feet on the.c stree.ct.c
b = $(patsubst %.c,%.o,$(a))

• b is feet on the.o stree.ct.o

---

a = feet on the.c stree.ct.c
b = $(a:.c=.o)

• b is feet on the.o stree.ct.o

---

a = feet on the.c stree.ct.c
b = $(subst ee,EE,$(a))

• b is fEEt on the.c stEE.ct.c

---

a = feet on the.c stree.ct.c
b = $(subst .c,.o,$(a))

• b is feet on the.o stEE.ot.o

Environment Variables

foo += bar

• make, then foo is bar
• make foo=abc, then foo is abc
• foo=abc make, then foo is abc bar