Makefile Writing Essentials

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Understanding, do not spray

Recently tidied up their files, found that because of too lazy reasons, a lot of information is too late to tidy up forget, it is a pity, so, in the collation of makefile, as a novice, write makefile some questions immediately write down.

1 Assigning values to variables

Varname= is the most basic assignment.
varname: = is the value before overwriting
varname= is the value after the equals sign if it is not assigned
varname+ = is the value after adding an equal sign

2 meaning of several special symbols

< Span style= "FONT-FAMILY:VERDANA,ARIAL,HELVETICA,SANS-SERIF; font-size:14px; line-height:21px "> [email protected" target file,

< Span style= "FONT-FAMILY:VERDANA,ARIAL,HELVETICA,SANS-SERIF; font-size:14px; line-height:21px "> $^--all dependent files,

< Span style= "FONT-FAMILY:VERDANA,ARIAL,HELVETICA,SANS-SERIF; font-size:14px; line-height:21px "> $<--the first dependent file.

3 Multi-Catalog Makefile Writing Essentials

With command: ${make}-C ${subdirectory} ${targetname}

Note: The above command switches to subdirectories and executes the make command

Build makefile in subdirectories and work well on dependencies

4 Makefile Partial function use

patsubst (<pattern>,< replacement>,<text>)
Function: Find words in <text> (word with "space", "tab" or "carriage return" NewLine "delimited" is  
conforms to pattern <pattern> if matched, it is replaced with <replacement>. Here,<pattern> can include   the
wildcard character "%", which represents any length of string. If <replacement> also contains "%", then  
<replacement> This "%" will be the string represented by the "%" in <pattern>. (You can use "\" &NBSP;
to escape, "\%" to represent the true meaning of the "%" character)  
Returns: The function returns the string that was replaced.

Example:
$ (patsubst%.c,%.o,tmp.c.c tmp1.c)
Replace the word string "tmp.c.c tmp1.c" with [%.c] with [%.O] and return the result "tmp.c.o tmp1.o"

$ (strip <string>)

Function: Remove the empty characters from the beginning and end of the <string> string.
Return: Returns the string value of the stripped space.
Example:
$ (Strip ABC)
The string "abc" goes to the beginning and end of the space, the result is "ABC".

${wildcard <partner>)

Function: src = $ (wildcard *.c)

Returns: searches all files in the current directory that end in. C, generates a list of file names separated by spaces, and assigns them to SRC. The current directory file has only a file name, and the file name under the subdirectory contains the path information

${notdir textlist)

Use: src = $ (notdir textlist)

Returns: Removes all directory information, the file name list in SRC will have only the filename.

Examples of my makefile:

Topdir-makefile:

##############################
# File:makefile
# Author:sky
# modified-date:2016-05-07
###############################
Export Root_dir: = $ (shell pwd)
#get out of start and end Char ' of the string
Root_dir: =$ (Strip ${root_dir})
Export lib_dir:=$ (Root_dir)/lib
Export src_dir:=$ (Root_dir)/src
Export include_dir:=$ (Root_dir)/include
Export Target:=test
Export CC:=GCC
Export Ld_flags:=-l Config-pthread
Export src:=$ (wildcard ${src_dir}/*.c)
Export obj:=$ (Patsubst%.c,%.o,${src})
Export OBJ_S:=Y_START.O Y_CHILDPROCESS.O
#if you want to build Release-program, use Command:make build_release=true
Ifeq ($ (build_release), TRUE)
Export c_flags:=-I ${include_dir}-std=c99
Export Build_dir: = $ (Root_dir)/release
Else
Export c_flags:=-g-d y_debug-i ${include_dir}-std=c99
Export Build_dir: = $ (Root_dir)/debug
endif
Export old_obj:=$ (wildcard ${BUILD_DIR}/*.O)
. Phony:d efault All clean
Default:all
All:
@${make}-c src all
Clean
@${make}-c src clean
Sub-dir-makefile:

. Phony:all Clean
All:${target}
@${cc} ${obj}-o ${target} ${ld_flags}
@mv ${target} ${build_dir}
@mv ${obj} ${build_dir}
#this is to do test from a static-lib
Test_static:${obj}
@${cc} ${c_flags} ${obj_s}-o test_static-static-l ${lib_dir}-L Y_stdio
#this is to do test from a shared-lib
Test_share:${obj}
@${cc} ${c_flags} ${obj_s}-o test_share-l ${lib_dir}-L Y_stdio
#this is to make a static-lib
Liby_stdio_static:
@${cc} ${c_flags}-C Y_STDIO.C
@ar-rcs liby_stdio.a y_stdio.o
@mv LIBY_STDIO.A ${lib_dir}
#this is to make a shared-lib
Liby_stdio_shared:
@${cc} ${c_flags}-fpic-c y_stdio.c
@${cc}-shared-fpic-o liby_stdio.so y_stdio.o
@mv liby_stdio.so ${lib_dir}
${target}:
@${cc} ${c_flags}-C ${SRC}
#clean Target
Clean
@rm ${old_obj} ${build_dir}/${target}

The pure hand dozen, inevitably has the mistake place, welcome correct correction.

#PS: Please respect the original, do not like to spray

#PS: To reprint please specify the source, I all rights reserved

If you have any questions, please leave a message and I will reply when I see it.

Makefile Writing Essentials