Members of Dirent structure

Question

I have started working with dirent.h library and I came across a very useful member of "struct dirent" structer which struct dirent *p->d_name in my book. But unfortunatly it doesn't states any other members of this structure;

I was wondering what else are the members of this structure and what are they used for?

Regards

I assume you're on Linux. In that case, simply read the dirent.h manual page (`man dirent.h`). — Nikos C., Oct 20 '12 at 18:25
@Hi-Angel You're missing the POSIX man-pages package. (Whatever it's called in your Linux distro. On mine (Gentoo), it's sys-apps/man-pages-posix). — Nikos C., Nov 14 '14 at 20:12
@NikosC. wow, I never knew that here's more than the default manual pages. Indeed, on my Kubuntu it was the package `manpages-posix-dev`. — Hi-Angel, Nov 15 '14 at 08:59

score 38 · Accepted Answer · answered Oct 20 '12 at 18:31

38

The structure, struct dirent refers to directory entry.

http://www.gnu.org/software/libc/manual/html_node/Directory-Entries.html

In linux it is defined as:

struct dirent {
    ino_t          d_ino;       /* inode number */
    off_t          d_off;       /* offset to the next dirent */
    unsigned short d_reclen;    /* length of this record */
    unsigned char  d_type;      /* type of file; not supported
                                   by all file system types */
    char           d_name[256]; /* filename */
};

refer: man readdir

Or just look for "dirent.h" in the include directory.

answered Oct 20 '12 at 18:31

askmish

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As written in another answer, only `d_ino` and `d_name` are [POSIX](https://en.wikipedia.org/wiki/POSIX). The rest should be avoided, or at worse used very cautiously, and only if you understand the implications. – 7heo.tk May 26 '14 at 14:48
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The rest of the fields are needed just for extremely simple things (like determining if an entry refers to a file or a sub-directory), and telling people not to use any of the other fields is pointless (because they almost always must use them). – Brendan Mar 05 '19 at 22:01

score 5 · Answer 2 · answered Oct 20 '12 at 18:20

5

There are only two members (from wikipedia):

ino_t d_ino - file serial number
char d_name[] - name of entry (will not exceed a size of NAME_MAX)

Take a look at the unix spec as well.

answered Oct 20 '12 at 18:20

MByD

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There might be some other (implementation or system specific) members, but you should not use them for POSIX portability reasons. – Basile Starynkevitch Oct 20 '12 at 20:23

score 1 · Answer 3 · answered Oct 20 '12 at 18:22

1

in addition to above answer of @Binyamin Sharet:

 off_t d_off - file offset
    unsigned short int d_reclen - length of the dirent record
    unsigned short int d_namlen - length of name
    unsigned int d_type - type of file

answered Oct 20 '12 at 18:22

Ravindra Bagale

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These should not be used. They are implementation-specific and not defined by POSIX. You should probably update your answer to reflect that. – Nikos C. Oct 20 '12 at 18:30
some filesystems (e.g. ext4, xfs) in some configurations (usually at mkfs time) can deliver the type of (some or all) the directory entries (the DT_* symbols). If not known, they are DT_UNKNOWN. The d_type member is not portable, but nevertheless widely available. – Remember Monica Oct 09 '15 at 16:31

Members of Dirent structure

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