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fork.c
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fork.c
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#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<sys/types.h>
#include<unistd.h>
void parse(char *line,char **argv){
while(*line!='\0'){
while(*line==' ' || *line=='\n' || *line=='\t')
*line++='\0';
*argv++=line;
while(*line!=' ' && *line!='\t' && *line!='\0' && *line!='\n')
line++;
}
*argv='\0';
}
void execute(char **argv){
pid_t pid,wpid;
int status;
printf("Forking a child\n");
pid=fork();
printf("Command line process id is %d\n",pid);
if(pid<0){
perror("fork failed\n");
exit(1);
}
else if(pid==0){
printf("Executing the command %s in child\n",argv[0]);
if(execvp(argv[0],argv)==-1){
perror("execvp failed\n");
exit(1);
}
}
else{
do{
printf("In parent waiting for child to execute\n");
wpid=waitpid(pid,&status,WUNTRACED);
}while(!WIFEXITED(status) && !WIFSIGNALED(status));
}
return;
}
main(void)
{
char line[1024];
char *argv[64];
while(1){
printf("Shell->\n");
gets(line);
parse(line,argv);
if(strcmp(line,"exit")==-1)
exit(1);
execute(argv);
}
}