I have a C source file with some functions in it. I want to call some particular function from a shell script.
I have a sample.c file with the below content. I want to call funcA here from a shell script. How can I do that?
#include <stdio.h>
void funcA(void){
printf("Congrats..!! This is function A...!!\n");
}
int main(void){
printf("Better luck next time..!!\n");
return 0;
}
If you are willing to change your code a bit by adding a call to the exit function (e.g. exit(0);) at the end of the functions, you can compile your code by passing the -e funcA option to the linker to make their entry point funcA in this case.
Assuming the file being called foo.c, you can then have the following shell script which executes the funcA function from the file foo.c upon calling call foo.c funcA from a shell script.
call() {
cc -Wl,-e"$2" $1 && ./a.out
}
It's not possible to call a function from a C binary/library directly from shell. Some languages support this (for example Python with ctypes) but I don't know any similar option for bash (or other shells).
You'll need to use command line options options and call the C program with an option/argument that tells your program to call a specific function.
So for your example you'll need to do something like
int main(int argc, char *argv[]) {
if (argc != 2) {
printf("Argument expected\n");
return 1;
}
if (strcmp (argv[1], "funcA") == 0)
funcA();
}
And then you can call it from shell like
$ ./a.out funcA
Congrats..!! This is function A...!!
