{"id":3864,"date":"2024-03-12T02:26:50","date_gmt":"2024-03-11T20:56:50","guid":{"rendered":"https:\/\/cthecosmos.com\/?p=3864"},"modified":"2024-03-12T02:26:50","modified_gmt":"2024-03-11T20:56:50","slug":"inode","status":"publish","type":"post","link":"https:\/\/cthecosmos.com\/?p=3864","title":{"rendered":"INode"},"content":{"rendered":"\n

The file system’s inode (index node) contains one inode for each file residing in the file system. An inode stores essential information, including:

o  File Type<\/strong>: Indicates if the entry is a regular file, directory, character device, or symbolic link.
o  File Size<\/strong>: Represents the size of the file in bytes.
o  Permissions<\/strong>: Specifies the read, write, and execute permissions for different users.
o  Owners and Groups<\/strong>: Stores the user and group IDs for the file’s owner and group.
o  Time Stamps<\/strong>: Records three timestamps: the last access time, the last modification time (content), and the last status change time (metadata).
o  File Modes<\/strong>: Includes permissions and special attributes associated with the file.
o  Number of Hard Links<\/strong>: Indicates the number of hard links pointing to the inode.
o  Pointers to Data Blocks<\/strong>: Stores pointers to the data blocks that contain the file’s actual content.
o  Number of Blocks Allocated<\/strong>: Represents the number of blocks allocated to the file.

The inode acts as a central data structure within the file system, encapsulating these crucial details about each file. In Linux, the stat system call is used to retrieve information about a file or directory. When stat<\/strong>() is called on a file or directory, it accesses the associated inode internally to populate the struct stat data structure.

struct stat {
dev_t    st_dev;        \/* ID of device containing file *\/
ino_t    st_ino;        \/* Inode number *\/
mode_t   st_mode;       \/* File type and mode *\/
nlink_t  st_nlink;      \/* Number of hard links *\/
uid_t    st_uid;        \/* User ID of owner *\/
gid_t    st_gid;        \/* Group ID of owner *\/
dev_t    st_rdev;       \/* Device ID (if special file) *\/
off_t    st_size;       \/* Total size, in bytes *\/
blksize_t st_blksize;    \/* Block size for filesystem I\/O *\/
blkcnt_t st_blocks;     \/* Number of 512B blocks allocated *\/

struct timespec st_atim; \/* Time of last access *\/
struct timespec st_mtim; \/* Time of last modification *\/
struct timespec st_ctim; \/* Time of last status change *\/

#define<\/a> st_atime st_atim.tv_sec     \/* Backward compatibility *\/
#define<\/a> st_mtime st_mtim.tv_sec
#define<\/a> st_ctime st_ctim.tv_sec
};

This struct stat contains fields that correspond to various attributes and metadata of a file. By utilizing the stat system call and accessing the inode internally, we can retrieve information about files and directories in a file system.

<\/p>\n\n\n\n

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
An Article by: <\/strong>Yashwanth Naidu Tikkisetty
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~<\/p>\n","protected":false},"excerpt":{"rendered":"

The file system’s inode, a central data structure, holds crucial file details such as type, size, permissions, owners, timestamps, links, data block pointers, and allocated blocks. In Linux, the stat system call accesses the inode to retrieve file information using the struct stat data structure. This enables gathering details about files and directories in the file system.<\/p>\nRead More INode<\/span><\/a>","protected":false},"author":120055267,"featured_media":3867,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_wpcom_ai_launchpad_first_post":false,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"{title}\n\n{excerpt}\n\n{url}","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"_wpas_customize_per_network":false,"jetpack_post_was_ever_published":false},"categories":[30181,769114260],"tags":[772321193,2431138,34922710,14237838,34920936],"class_list":["post-3864","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-embedded-systems","category-linuxlearnings","tag-embedded-systems","tag-inode","tag-linux-2","tag-os-2","tag-ubuntu-2","fallback-thumbnail"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t