How to configure make to execute a specific compilation command?

Question

When executing

make prog

in the same directory as my source code file named prog.c, I see this command gets executed

gcc prog.c -o prog

which leads to causing various compile-time errors from being not able to use for loops to undefined reference to the functions of the cs50 library.

How to fix this?

Answer 1

Two ways to configure make to execute a specific compilation command with specific options are:

1. Makefiles
2. Environment Variables

Assuming you have a source code file of a C program named prog.c, to manually configure make to execute the same compilation command as the one in the lectures follow either of the following ways:

Configuring make Using Makefiles

1. create a file named Makefile in the same directory as your program and paste the following text in it

   prog: prog.c
       clang -ggdb3 -O0 -std=c99 -Wall -Werror prog.c -lcs50 -lm -o prog
   

NOTE: the second line starts with a tab not spaces

2. save the file.

Configuring make Using Environment Variables

Two ways of achieving this are

1. temporarily setting the values of some environment variables
2. permanently setting the values of these environment variables.

Configuring make Temporarily

Open up a terminal window and execute these commands

export CC="clang"
export CFLAGS="-ggdb3 -O0 -std=c99 -Wall -Werror"
export LDLIBS="-lcs50 -lm"

Configuring make Permanently

1. Open up the terminal window and execute these commands

   cd
   sudo gedit .profile
   

NOTE: if asked to enter a password, enter "crimson"

2. paste the following lines at the end of the file

   export CC="clang"
   export CFLAGS="-ggdb3 -O0 -std=c99 -Wall -Werror -Wno-unused-variable"
   export LDLIBS="-lcs50 -lm"
   

3. log off and log back in