I'm trying to write a history feature to a very simple UNIX shell that will list the last 10 commands used when control-c is pressed. A user can then run a previous command by typing r x, where x is the first letter of the command. I'm having quite a bit of trouble figuring out what I need to do, I have very little C experience, but I know a fair bit of C++. If anyone could give me some suggestions as to where to start, I'd appreciate it. Here is the code I'm working from right now.

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

#define MAX_LINE 80 /* 80 chars per line, per command */
#define BUFFER_SIZE 50
char buffer[BUFFER_SIZE];


/* the signal handling function */
void handle_SIGINT()
{
write(STDOUT_FILENO, buffer, strlen(buffer));

}


/**
* setup() reads in the next command line, separating it into distinct tokens
* using whitespace as delimiters. setup() sets the args parameter as a
* null-terminated string.
*/

void setup(char inputBuffer[], char *args[],int *background)
{
int length, /* # of characters in the command line */
i, /* loop index for accessing inputBuffer array */
start, /* index where beginning of next command parameter is */
ct; /* index of where to place the next parameter into args[] */

ct = 0;

/* read what the user enters on the command line */
length = read(STDIN_FILENO, inputBuffer, MAX_LINE);

start = -1;
if (length == 0)
exit(0); /* ^d was entered, end of user command stream */
if (length < 0){
perror("error reading the command");
exit(-1); /* terminate with error code of -1 */
}

/* examine every character in the inputBuffer */
for (i=0;i<length;i++) {
switch (inputBuffer[i]){
case ' ':
case '\t' : /* argument separators */
if(start != -1){
args[ct] = &inputBuffer[start]; /* set up pointer */
ct++;
}
inputBuffer[i] = '\0'; /* add a null char; make a C string */
start = -1;
break;

case '\n': /* should be the final char examined */
if (start != -1){
args[ct] = &inputBuffer[start];
ct++;
}
inputBuffer[i] = '\0';
args[ct] = NULL; /* no more arguments to this command */
break;

default : /* some other character */
if (start == -1)
start = i;
if (inputBuffer[i] == '&'){
*background = 1;
inputBuffer[i] = '\0';
}
}
}
args[ct] = NULL; /* just in case the input line was > 80 */
}

int main()
{
char inputBuffer[MAX_LINE]; /* buffer to hold the command entered */
int background; /* equals 1 if a command is followed by '&' */
char *args[MAX_LINE/2 +1];
pid_t pid;

/* set up the signal handler */
struct sigaction handler;
handler.sa_handler = handle_SIGINT;
sigaction(SIGINT, &handler, NULL);

while (1){ /* Program terminates normally inside setup */
background = 0;
printf(" sh>\n");
setup(inputBuffer,args,&background); /* get next command */

/* the steps are:
(1) fork a child process using fork() */
pid = fork();

if(pid == 0){ /* child process (2) the child process will
invoke execvp()*/
execvp(args[0], args);
exit(0);
}
else if(pid > 0){ /*parent process (3) if background == 1, the parent
will wait, otherwise returns to the setup() function.
*/
if(background == 1){
wait(NULL);

}/* if */
}/* if */
}
}