程序人生 | UNIX环境高级编程技巧之 df 指令实现 c

本文首发于 2014-07-10 09:48:48

代码

#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

$ gcc -g -Wall testdf.c -o testdf

运行

testdf执行效果：

$ ./testdf FilesystemSizeUsed Available Use% Mounted on udev3.87 GB0.00 B3.87 GB0% /dev tmpfs796.17 MB980.00 K 795.21 MB0% /run /dev/vda196.75 GB40.54 GB56.19 GB42% / tmpfs3.89 GB0.00 B3.89 GB0% /dev/shm tmpfs5.00 MB0.00 B5.00 MB0% /run/lock tmpfs3.89 GB0.00 B3.89 GB0% /sys/fs/cgroup /dev/vda15104.35 MB3.86 MB 100.50 MB4% /boot/efi /dev/loop155.50 MB55.50 MB0.00 B 100% /snap/core18/2074 /dev/loop270.62 MB70.62 MB0.00 B 100% /snap/lxd/16922 /dev/loop470.38 MB70.38 MB0.00 B 100% /snap/lxd/21029 /dev/loop532.38 MB32.38 MB0.00 B 100% /snap/snapd/12704 tmpfs796.17 MB980.00 K 795.21 MB0% /run/snapd/ns tmpfs796.17 MB0.00 B 796.17 MB0% /run/user/1000 /dev/loop655.50 MB55.50 MB0.00 B 100% /snap/core18/2128 /dev/loop032.38 MB32.38 MB0.00 B 100% /snap/snapd/12883

原生df执行效果：

$ df -h FilesystemSizeUsed Avail Use% Mounted on udev3.9G03.9G0% /dev tmpfs797M980K796M1% /run /dev/vda197G41G57G42% / tmpfs3.9G03.9G0% /dev/shm tmpfs5.0M05.0M0% /run/lock tmpfs3.9G03.9G0% /sys/fs/cgroup /dev/vda15105M3.9M101M4% /boot/efi /dev/loop156M56M0 100% /snap/core18/2074 /dev/loop271M71M0 100% /snap/lxd/16922 /dev/loop471M71M0 100% /snap/lxd/21029 /dev/loop533M33M0 100% /snap/snapd/12704 tmpfs797M0797M0% /run/user/1000 /dev/loop656M56M0 100% /snap/core18/2128 /dev/loop033M33M0 100% /snap/snapd/12883

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