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NAME |LIBRARY |SYNOPSIS |DESCRIPTION |RETURN VALUE |ERRORS |STANDARDS |HISTORY |NOTES |EXAMPLES |SEE ALSO |COLOPHON | |
getdents(2) System Calls Manualgetdents(2)getdents, getdents64 - get directory entries
Standard C library (libc,-lc)
#include <sys/syscall.h>/* Definition ofSYS_*constants */#include <unistd.h>long syscall(SYS_getdents, unsigned intfd, struct linux_dirent *dirp,unsigned intcount);#define _GNU_SOURCE/* See feature_test_macros(7) */#include <dirent.h>ssize_t getdents64(size_t count;intfd, voiddirp[count], size_tcount);Note: glibc provides no wrapper forgetdents(), necessitating the use ofsyscall(2).Note: There is no definition ofstruct linux_dirent in glibc; see NOTES.
These are not the interfaces you are interested in. Look atreaddir(3) for the POSIX-conforming C library interface. This page documents the bare kernel system call interfaces.getdents() The system callgetdents() reads severallinux_dirent structures from the directory referred to by the open file descriptorfd into the buffer pointed to bydirp. The argumentcount specifies the size of that buffer. Thelinux_dirent structure is declared as follows: struct linux_dirent { unsigned long d_ino; /* Inode number */ unsigned long d_off; /* Not an offset; see below */ unsigned short d_reclen; /* Length of thislinux_dirent */ char d_name[]; /* Filename (null-terminated) */ /* length is actually (d_reclen - 2 - offsetof(struct linux_dirent, d_name)) */ /* char pad; // Zero padding byte char d_type; // File type (only since Linux // 2.6.4); offset is (d_reclen - 1) */ }d_ino is an inode number.d_off is a filesystem-specific value with no specific meaning to user space, though on older filesystems it used to be the distance from the start of the directory to the start of the nextlinux_dirent; seereaddir(3).d_reclen is the size of this entirelinux_dirent.d_name is a null-terminated filename.d_type is a byte at the end of the structure that indicates the file type. It contains one of the following values (defined in<dirent.h>):DT_BLKThis is a block device.DT_CHRThis is a character device.DT_DIRThis is a directory.DT_FIFO This is a named pipe (FIFO).DT_LNKThis is a symbolic link.DT_REGThis is a regular file.DT_SOCK This is a UNIX domain socket.DT_UNKNOWN The file type is unknown. Thed_type field is implemented since Linux 2.6.4. It occupies a space that was previously a zero-filled padding byte in thelinux_dirent structure. Thus, on kernels up to and including Linux 2.6.3, attempting to access this field always provides the value 0 (DT_UNKNOWN). Currently, only some filesystems (among them: Btrfs, ext2, ext3, and ext4) have full support for returning the file type ind_type. All applications must properly handle a return ofDT_UNKNOWN.getdents64() The original Linuxgetdents() system call did not handle large filesystems and large file offsets. Consequently, Linux 2.4 addedgetdents64(), with wider types for thed_ino andd_off fields. In addition,getdents64() supports an explicitd_type field. Thegetdents64() system call is likegetdents(), except that its second argument is a pointer to a buffer containing structures of the following type: struct linux_dirent64 { ino64_t d_ino; /* 64-bit inode number */ off64_t d_off; /* Not an offset; see getdents() */ unsigned short d_reclen; /* Size of this dirent */ unsigned char d_type; /* File type */ char d_name[]; /* Filename (null-terminated) */ };On success, the number of bytes read is returned. On end of directory, 0 is returned. On error, -1 is returned, anderrno is set to indicate the error.
EBADFInvalid file descriptorfd.EFAULTArgument points outside the calling process's address space.EINVALResult buffer is too small.ENOENTNo such directory.ENOTDIR File descriptor does not refer to a directory.
None.
SVr4.getdents64() glibc 2.30.
glibc does not provide a wrapper forgetdents(); callgetdents() usingsyscall(2). In that case you will need to define thelinux_dirent orlinux_dirent64 structure yourself. Probably, you want to usereaddir(3) instead of these system calls. These calls supersedereaddir(2).
The program below demonstrates the use ofgetdents(). The following output shows an example of what we see when running this program on an ext2 directory: $./a.out /testfs/ --------------- nread=120 --------------- inode# file type d_reclen d_off d_name 2 directory 16 12 . 2 directory 16 24 .. 11 directory 24 44 lost+found 12 regular 16 56 a 228929 directory 16 68 sub 16353 directory 16 80 sub2 130817 directory 16 4096 sub3Program source #define _GNU_SOURCE #include <dirent.h> /* Defines DT_* constants */ #include <err.h> #include <fcntl.h> #include <stdint.h> #include <stdio.h> #include <stdlib.h> #include <sys/syscall.h> #include <sys/types.h> #include <unistd.h> struct linux_dirent { unsigned long d_ino; off_t d_off; unsigned short d_reclen; char d_name[]; }; #define BUF_SIZE 1024 int main(int argc, char *argv[]) { int fd; char d_type; char buf[BUF_SIZE]; long nread; struct linux_dirent *d; fd = open(argc > 1 ? argv[1] : ".", O_RDONLY | O_DIRECTORY); if (fd == -1) err(EXIT_FAILURE, "open"); for (;;) { nread = syscall(SYS_getdents, fd, buf, BUF_SIZE); if (nread == -1) err(EXIT_FAILURE, "getdents"); if (nread == 0) break; printf("--------------- nread=%ld ---------------\n", nread); printf("inode# file type d_reclen d_off d_name\n"); for (size_t bpos = 0; bpos < nread;) { d = (struct linux_dirent *) (buf + bpos); printf("%8lu ", d->d_ino); d_type = *(buf + bpos + d->d_reclen - 1); printf("%-10s ", (d_type == DT_REG) ? "regular" : (d_type == DT_DIR) ? "directory" : (d_type == DT_FIFO) ? "FIFO" : (d_type == DT_SOCK) ? "socket" : (d_type == DT_LNK) ? "symlink" : (d_type == DT_BLK) ? "block dev" : (d_type == DT_CHR) ? "char dev" : "???"); printf("%4d %10jd %s\n", d->d_reclen, (intmax_t) d->d_off, d->d_name); bpos += d->d_reclen; } } exit(EXIT_SUCCESS); }readdir(2),readdir(3),inode(7)
This page is part of theman-pages (Linux kernel and C library user-space interface documentation) project. Information about the project can be found at ⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report for this manual page, see ⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩. This page was obtained from the tarball man-pages-6.15.tar.gz fetched from ⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on 2025-08-11. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up- to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which isnot part of the original manual page), send a mail to man-pages@man7.orgLinux man-pages 6.15 2025-06-28getdents(2)Pages that refer to this page:readdir(2), syscalls(2), readdir(3), proc(5), proc_pid_task(5)
HTML rendering created 2025-09-06 byMichael Kerrisk, author ofThe Linux Programming Interface. For details of in-depthLinux/UNIX system programming training courses that I teach, lookhere. Hosting byjambit GmbH. | |