我正在製作一個簡單的shell。它還需要能夠按行讀取文本文件。這是我的代碼:fgets在退出EOF之前多次循環
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/stat.h>
// Exit when called, with messages
void my_exit() {
printf("Bye!\n");
exit(0);
}
int main(void) {
setvbuf(stdout, NULL, _IONBF, 0);
// Char array to store the input
char buff[1024];
// For the fork
int fid;
// Get all the environment variables
char dir[50];
getcwd(dir,50);
char *user = getenv("USER");
char *host = getenv("HOST");
// Issue the prompt here.
printf("%[email protected]%s:%s> ", user, host, dir);
// If not EOF, then do stuff!
while (fgets(buff, 1024, stdin) != NULL) {
// Get rid of the new line character at the end
// We will need more of these for special slash cases
int i = strlen(buff) - 1;
if (buff[i] == '\n') {
buff[i] = 0;
}
// If the text says 'exit', then exit
if (!strcmp(buff,"exit")) {
my_exit();
}
// Start forking!
fid = fork();
// If fid == 0, then we have the child!
if (fid == 0) {
// To keep track of the number of arguments in the buff
int nargs = 0;
// This is a messy function we'll have to change. For now,
// it just counts the number of spaces in the buff and adds
// one. So (ls -a -l) = 3. AKA 2 spaces + 1. Really in the
// end, we should be counting the number of chunks in between
// the spaces.
for (int i = 0; buff[i] != '\0'; i++) {
if (buff[i] == ' ') nargs ++;
}
// Allocate the space for an array of pointers to args the
// size of the number of args, plus one for the NULL pointer.
char **args = malloc((sizeof(char*)*(nargs + 2)));
// Set the last element to NULL
args[nargs+1] = NULL;
// Split string into tokens by space
char *temp = strtok (buff," ");
// Copy each token into the array of args
for (int i = 0; temp != NULL; i++) {
args[i] = malloc (strlen(temp) + 1);
strcpy(args[i], temp);
temp = strtok (NULL, " ");
}
// Run the arguments with execvp
if (execvp(args[0], args)) {
my_exit();
}
}
// If fid !=0 then we still have the parent... Need to
// add specific errors.
else {
wait(NULL);
}
// Issue the prompt again.
printf("%[email protected]%s:%s> ", user, host, dir);
}
// If fgets == NULL, then exit!
my_exit();
return 0;
}
當我單獨運行它作爲一個shell,它工作的很好。當我運行./myshell < commands.txt時,它不起作用。
commands.txt中是:
ls -l -a
pwd
ls
但輸出是:
>Bye!
>Bye!
>Bye!
>Bye!
>Bye!
>Bye!>Bye!
>Bye!
>Bye!
>Bye!
甚至不運行我的命令。有任何想法嗎?我認爲我的while循環非常簡單。
嘗試並在my_exit()中打印進程的PID以查看誰在打印什麼。 –
在打印提示後至少需要刷新輸出,以便它在相對於命令輸出的正確位置出現。 –
打印PID,除了最後一個,我得到全0(每個再見!),這是19147 – user1687558