如何在Linux环境中使用C chdir [英] How to chdir using C in Linux environment

问题描述

我是C语言编程的新手.当我有 $ ans 是我不能 chdir /home/jobs/$ ans/xxx/>在C程序中.

I am new in c programming. How can I change directory like /home/jobs/$ans/xxx/ while I have $ans is a user string I can't chdir in c program.

我的脚本在下面:

#include <stdio.h>
#include <stdlib.h>

int main()
{
    char jdir;
    printf("Enter job directory:");  /* user input for different directories */
    scanf("jdir");
    chdir("/home/jobs/%jdir/xxx");
    system("ls -ltr");
    return(0);
}

如何使用 chdir 更改目录?

推荐答案

用C编写该程序似乎有些愚蠢，但是如果有充分的理由(例如，必须设置setuid)，那么您应该对此更具防御性.我会做这样的事情:

It seems mildly silly to write this program in C, but if there is a good reason to do so (for instance if it has to be setuid) then you should be a great deal more defensive about it. I would do something like this:

#define _XOPEN_SOURCE 700 /* getline */
#include <stdio.h>
#include <string.h>
#include <unistd.h>

int main(void)
{
    char *jobdir = 0;
    size_t asize = 0;
    ssize_t len;

    fputs("Enter job directory: ", stdout);
    fflush(stdout);
    len = getline(&jobdir, &asize, stdin);
    if (len < 0) {
        perror("getline");
        return 1;
    }

    jobdir[--len] = '\0'; /* remove trailing \n */
    if (len == 0 || !strcmp(jobdir, ".") || !strcmp(jobdir, "..")
        || strchr(jobdir, '/')) {
        fputs("job directory name may not be empty, \".\", or \"..\", "
              "nor contain a '/'\n", stderr);
        return 1;
    }

    if (chdir("/home/jobs") || chdir(jobdir) || chdir("xxx")) {
        perror(jobdir);
        return 1;
    }
    execlp("ls", "ls", "-ltr", (char *)0);
    perror("exec");
    return 1;
}

此答案的编辑历史将显示出100％正确的解决方法有多困难-我一直坚持下去，并意识到我忘记了另一件需要辩护的案件.

The edit history of this answer will demonstrate just how hard it is to get this 100% right - I keep coming back to it and realizing that I forgot yet another case that needs to be defended against.

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