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，或者更常见地分配给 make 将被扩展以形成链接命令的变量.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 是您要链接的库的名称.

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

例如，如果您想链接到库 ~/libs/libabc.a，您需要添加:

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

-L$(HOME)/libs -labc

要利用默认的隐式链接规则，请将这些标志添加到变量 LDFLAGS，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

<小时>

把LDFLAGS和LIBS分开是个好习惯，例如

---

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 $@

即使它可能以其他方式工作，-l... 指令也应该在引用这些符号的对象之后.如果链接以错误的顺序完成，一些优化(-Wl,--as-needed 是最明显的)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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