Trouble with pointers In C. Segmentation fault -

i'm having trouble project university consists in simulating shell. user types command , program divides line in tokens , checks if 1 of them internal command, such cd, export, jobs , source. prints tokens , basic explanation of command has been found in line. when run on codeblocks works fine, when compile on netbeans in linux, reports several warnings, explain in code , when run message appears: segmentation fault (core dumped). i've been researching , i've found has memory permissions (accessing part of memory not allowed access). can't find way solve it, hope here can me. thanks!

#include <stdio.h> #include <stdlib.h> #define prompt "$"  int parse_args(char **args, char *line){     char *token;     int n=0;     token=strtok(line," "); // warning: assignment makes pointer integer without cast     while(token!=null){         printf("token%i: %s\n",n,token);         *args=token;         n++;         *args++;         token=strtok(null," ");// warning: assignment makes pointer integer without cast     }     printf("token%i: %s\n",n,token);     *args=token;     return n; }  char *read_line(char *line){ //expecting argument char* argument of type char**     printf("%s ",prompt);         *line = malloc(sizeof(500));//warning: assignment makes pointer integer without cast     fgets(line,500,stdin);     return line; }   int execute_line(char *line){//expecting argument char* argument of type char**     char**args;     parse_args(args,line);     check_internal(args);     return 0; }  int check_internal(char **args){     if( strcmp(*args, "cd")==0 ){  internal_cd();     } else{         if( strcmp(*args, "export")==0 ){             internal_export();         }else{             if( strcmp(*args, "source")==0 ){                 internal_source();             }else{                 if( strcmp(*args, "jobs")==0 ){                     internal_jobs();                 }else{                     printf("%s","pasa los ifelse\n");                     return 0;                 }             }         }     } }   int internal_cd(char **args){     printf("%s","cambio de directorio\n");     return 1; }  int internal_export(char **args) {     printf("%s","éste es el export\n");     return 1; }  int internal_source(char **args) {     printf("%s","éste es el source\n");     return 1; }  int internal_jobs(char **args){     printf("%s","éste es el jobs\n");     return 1; }  void main(){     char *line;     while(read_line(&line)){//warning: imcompatible pointer type         execute_line(&line);//warning: incompatible pointer type     }     //free line here?? } 

your problem twofold.

first, design function take char * expect accept char **, like

char *read_line(char *line) 

and

read_line(&line); 

same goes execute_line() also.

secondly,

 malloc(sizeof(500)); 

is same as

malloc(sizeof(int)); 

what want instead

 malloc(500); 

as malloc() takes argument size of memory allocated in bytes.