CODEWITHSUNDEEP
clinuxbashshell
RaXenel
RaXenel

Reputation: 1

Using arguments in bash from C command line

Is it even possible to transfer command line arguments with execl from C to bash? cuz with C to C file i was getting exect formatt error. so decided to try C main, and bash son script, everything is running fine, except that i can't figure out how to transfer that argv with execl and than use it with son..

FATHER

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <unistd.h>

main( int argc, char *argv[])
{
    int pid;

    if (argc==4)
    {
        printf ("Need to enter 3 arguments");
        printf ("\tOne Process yet, creating second...\n");
        pid = fork();
    }
    else
    {
        printf ("Need to give me 3 arguments\n");
        exit(EXIT_FAILURE);

    }
    if(pid==0)
    {
        printf("\tChild process launched...\n");
        execl("./testB", "testB", argv[1], argv[2], argv[3], NULL);
        perror("execl dissapointed us");
    }
    else if(pid>0)
    {
        printf ("\twaiting for my child to finish...\n");
        wait((int *)0);
        printf("\t Child finished, time for father...\n");
        printf("Main Father\n");
    }
    else
    {
        printf("We've got an error, boss\n");
    }
    printf("Two proccesses?\n");
    printf("Number of arguments %d", argc);
}

SON 

#!/bin/bash
printf "im da testB\n"
echo "Iveskite norima kieki konvertacijai"
read litai
while [ "$litai" -le 0 ]
do
echo "Iveskite norima kieki konvertacijai"
read litai
done
SUM=$( echo "scale=4;$litai*3.4528" | bc )  
printf "Jusu pasirinktas litu kiekis %d atitinka %s eurus\n" "$litai"    "$SUM"
printf "asd %s\n" "$argv[1]"

Upvotes: 0

Views: 99

Answers (1)

alk
alk

Reputation: 70951

Change this

printf "asd %s\n" "$argv[1]"

to be

printf "asd %s\n" "$1"

to print the 1st argument passed to testB.

In bash arguments to the script are referred to by using $n with n starting with 1.

Also: The last parameter passed to execl() shall be (char*) NULL.

From man exec:

The list of arguments must be terminated by a null pointer, and, since these are variadic functions, this pointer must be cast (char *) NULL.

Upvotes: 1

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