中国电信成都营业网点:参考df代码写的一个简单的df命令的源代码
来源:百度文库 编辑:偶看新闻 时间:2024/06/11 07:49:47
参考df代码写的一个简单的df命令的源代码
作者:飞空静渡
df命令可以列出加载的磁盘或各种文件的信息:
下面给出一个简单的df的命令的源码,这个源码根据df的源码进行改写,很简单,就一个主文件 :)
view plaincopy to clipboardprint?
- #include
- #include
- #include
- #include
- static const unsigned long long G = 1024*1024*1024ull;
- static const unsigned long long M = 1024*1024;
- static const unsigned long long K = 1024;
- static char str[20];
- char* kscale(unsigned long b, unsigned long bs)
- {
- unsigned long long size = b * (unsigned long long)bs;
- if (size > G)
- {
- sprintf(str, "%0.2f GB", size/(G*1.0));
- return str;
- }
- else if (size > M)
- {
- sprintf(str, "%0.2f MB", size/(1.0*M));
- return str;
- }
- else if (size > K)
- {
- sprintf(str, "%0.2f K", size/(1.0*K));
- return str;
- }
- else
- {
- sprintf(str, "%0.2f B", size*1.0);
- return str;
- }
- }
- int main(int argc, char *argv[])
- {
- FILE* mount_table;
- struct mntent *mount_entry;
- struct statfs s;
- unsigned long blocks_used;
- unsigned blocks_percent_used;
- const char *disp_units_hdr = NULL;
- mount_table = NULL;
- mount_table = setmntent("/etc/mtab", "r");
- if (!mount_table)
- {
- fprintf(stderr, "set mount entry error/n");
- return -1;
- }
- disp_units_hdr = " Size";
- printf("Filesystem %-15sUsed Available %s Mounted on/n",
- disp_units_hdr, "Use%");
- while (1) {
- const char *device;
- const char *mount_point;
- if (mount_table) {
- mount_entry = getmntent(mount_table);
- if (!mount_entry) {
- endmntent(mount_table);
- break;
- }
- }
- else
- continue;
- device = mount_entry->mnt_fsname;
- mount_point = mount_entry->mnt_dir;
- //fprintf(stderr, "mount info: device=%s mountpoint=%s/n", device, mount_point);
- if (statfs(mount_point, &s) != 0)
- {
- fprintf(stderr, "statfs failed!/n");
- continue;
- }
- if ((s.f_blocks > 0) || !mount_table )
- {
- blocks_used = s.f_blocks - s.f_bfree;
- blocks_percent_used = 0;
- if (blocks_used + s.f_bavail)
- {
- blocks_percent_used = (blocks_used * 100ULL
- + (blocks_used + s.f_bavail)/2
- ) / (blocks_used + s.f_bavail);
- }
- /* GNU coreutils 6.10 skips certain mounts, try to be compatible. */
- if (strcmp(device, "rootfs") == 0)
- continue;
- if (printf("/n%-20s" + 1, device) > 20)
- printf("/n%-20s", "");
- char s1[20];
- char s2[20];
- char s3[20];
- strcpy(s1, kscale(s.f_blocks, s.f_bsize));
- strcpy(s2, kscale(s.f_blocks - s.f_bfree, s.f_bsize));
- strcpy(s3, kscale(s.f_bavail, s.f_bsize));
- printf(" %9s %9s %9s %3u%% %s/n",
- s1,
- s2,
- s3,
- blocks_percent_used, mount_point);
- }
- }
- return 0;
- }
编译:g++ -g -Wall main.cpp
可以生成一个a.out的文件,
下面是运行a.out和df -h的输出对比:
:/tmp/tmp$ df -h
文件系统 容量 已用 可用 已用% 挂载点
/dev/sda7 9.4G 6.5G 2.5G 73% /
none 1.6G 300K 1.6G 1% /dev
none 1.6G 212K 1.6G 1% /dev/shm
none 1.6G 296K 1.6G 1% /var/run
none 1.6G 0 1.6G 0% /var/lock
none 1.6G 0 1.6G 0% /lib/init/rw
/dev/sda6 113G 87G 26G 77% /media/work_
/dev/sda9 26G 23G 2.0G 92% /home
/tmp/tmp$ ./a.out
Filesystem Size Used Available Use% Mounted on
/dev/sda7 9.39 GB 6.45 GB 2.46 GB 72% /
none 1.59 GB 300.00 K 1.59 GB 0% /dev
none 1.60 GB 1020.00 K 1.59 GB 0% /dev/shm
none 1.60 GB 296.00 K 1.59 GB 0% /var/run
none 1.60 GB 0.00 B 1.60 GB 0% /var/lock
none 1.60 GB 0.00 B 1.60 GB 0% /lib/init/rw
/dev/sda6 112.62 GB 86.67 GB 25.95 GB 77% /media/work_
/dev/sda9 25.38 GB 22.10 GB 1.99 GB 92% /home