How to pass arguments to bash script from a cpp program

Question

I've forked a child process which then calls a bash script using execv, the way i'm passing command line arguments to the script, It does not print first argument on doing echo $1 inside the script.

std::string s = std::to_string(c_no);    
char *args[] = {(char *)s.c_str(), NULL};

pid_t pid = fork();
if(pid == 0){
    execv("./ckpnt.sh", &args[0]);
}

consider c_no to be any integer.

What is the correct way to do this?

I've already refrenced this link How to pass command line arguments from C program to the bash script? but this answer uses system system call and i try to not use that.

Botje · Accepted Answer · 2020-10-29 21:29:55Z

2

First argument passed to a program is its name so currently your number ends up in $0. args should be:

char *args[] = {"./ckpnt.sh", (char *)s.c_str(), NULL};

answered Oct 29, 2020 at 21:29

Botje

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17 Comments

ram Over a year ago

Still it doesn't print anything.

Botje Over a year ago

Works locally. Can you run the program under strace -Ff and see if it is passing arguments correctly?

ram Over a year ago

I just checked echo "$0" is printing ./ckpnt.sh but echo "$1" is not printing anything

Botje Over a year ago

Make sure you're properly recompiling, and again, check with strace -Ff to see what is being passed.

ram Over a year ago

the way i've passed arguments in exec line is correct ?

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