Write a C program that behaves like a shell which displays the command prompt ‘myshell$’. It accepts the command, tokenize the command line and execute it by creating the child process. Also implement the additional command ‘count’ as
myshell$ count c filename: It will display the number of characters in given file myshell$ count w filename: It will display the number of words in given file
myshell$ count l filename: It will display the number of lines in given file.
myshell$ count l filename: It will display the number of lines in given file.
Solution:
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
void make_toks(char *s, char *tok[])
{
int i=0;
char *p;
p = strtok(s," ");
while(p!=NULL)
{
tok[i++]=p;
p=strtok(NULL," ");
}
tok[i]=NULL;
}
void count(char *fn, char op)
{
int fh,cc=0,wc=0,lc=0;
char c;
fh = open(fn,O_RDONLY);
if(fh==-1)
{
printf("File %s not found.\n",fn);
return;
}
while(read(fh,&c,1)>0)
{
if(c==' ')
wc++;
else if(c=='\n')
{
wc++;
lc++;
}
cc++;
}
close(fh);
switch(op)
{
case 'c':
printf("No.of characters:%d\n",cc);
break;
case 'w':
printf("No.of words:%d\n",wc);
break;
case 'l':
printf("No.of lines:%d\n",lc);
break;
}
}
int main()
{
char buff[80],*args[10];
int pid;
while(1)
{
printf("myshell$");
fflush(stdin);
fgets(buff,80,stdin);
buff[strlen(buff)-1]='\0';
make_toks(buff,args);
if(strcmp(args[0],"count")==0)
count(args[2],args[1][0]);
else
{
pid = fork();
if(pid>0)
wait();
else
{
if(execvp(args[0],args)==-1)
printf("Bad command.\n");
exit(0);
}
}
}
return 0;
}
0 Comments:
Post a Comment