makefile中的-I和-L有什么区别? [英] What is the difference between -I and -L in makefile?

问题描述

makefile中-I和-L标志的用途是什么?

What is the usage of the -I and -L flags in a makefile?

推荐答案

这些通常是链接器命令行的一部分，或者直接在目标操作中提供，或者更常见的是分配给将要使用的make变量扩展为窗体链接命令.在这种情况下:

These are typically part of the linker command line, and are either supplied directly in a target action, or more commonly assigned to a make variable that will be expanded to form link command. In that case:

-L是包含库的目录的路径.库的搜索路径.

-L is the path to the directories containing the libraries. A search path for libraries.

-l是您要链接到的库的名称.

-l is the name of the library you want to link to.

例如，如果要链接到库~/libs/libabc.a，则要添加:

For instance, if you want to link to the library ~/libs/libabc.a you'd add:

-L$(HOME)/libs -labc

要利用默认的隐式规则进行链接，请将这些标志添加到变量LDFLAGS中，如

To take advantage of the default implicit rule for linking, add these flags to the variable LDFLAGS, as in

LDFLAGS+=-L$(HOME)/libs -labc

---

例如，分开LDFLAGS和LIBS是一个好习惯

---

It's a good habit to separate LDFLAGS and LIBS, for example

# LDFLAGS contains flags passed to the compiler for use during linking
LDFLAGS = -Wl,--hash-style=both
# LIBS contains libraries to link with
LIBS = -L$(HOME)/libs -labc
program: a.o b.o c.o
        $(CC) $(LDFLAGS) $^ $(LIBS) -o $@
        # or if you really want to call ld directly,
        # $(LD) $(LDFLAGS:-Wl,%=%) $^ $(LIBS) -o $@

即使它可以正常工作，也应该将-l...指令放在引用这些符号的对象的 之后.如果链接顺序错误，某些优化(-Wl,--as-needed最明显)将失败.

Even if it may work otherwise, the -l... directives are supposed to go after the objects that reference those symbols. Some optimizations (-Wl,--as-needed is the most obvious) will fail if linking is done in the wrong order.

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