man3type/stat.3type

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   7 .TH stat 3type 2022-07-22 "Linux man-pages (unreleased)" "Linux Programmer's Manual"
   8 .SH NAME
   9 stat \- file status
  10 .SH LIBRARY
  11 Standard C library
  12 .RI ( libc )
  13 .SH SYNOPSIS
  14 .nf
  15 .B #include <sys/stat.h>
  16 .PP
  17 .B struct stat {
  18 .BR "    dev_t      st_dev;" "      /* ID of device containing file */"
  19 .BR "    ino_t      st_ino;" "      /* Inode number */"
  20 .BR "    mode_t     st_mode;" "     /* File type and mode */"
  21 .BR "    nlink_t    st_nlink;" "    /* Number of hard links */"
  22 .BR "    uid_t      st_uid;" "      /* User ID of owner */"
  23 .BR "    gid_t      st_gid;" "      /* Group ID of owner */"
  24 .BR "    dev_t      st_rdev;" "     /* Device ID (if special file) */"
  25 .BR "    off_t      st_size;" "     /* Total size, in bytes */"
  26 .BR "    blksize_t  st_blksize;" "  /* Block size for filesystem I/O */"
  27 .BR "    blkcnt_t   st_blocks;" "   /* Number of 512 B blocks allocated */"
  28
  29     /* Since POSIX.1-2008, this structure supports nanosecond
  30        precision for the following timestamp fields.
  31        For the details before POSIX.1-2008, see VERSIONS. */
  32
  33 .BR "    struct timespec  st_atim;" "  /* Time of last access */"
  34 .BR "    struct timespec  st_mtim;" "  /* Time of last modification */"
  35 .BR "    struct timespec  st_ctim;" "  /* Time of last status change */"
  36
  37 .BR "#define st_atime  st_atim.tv_sec" "  /* Backward compatibility */"
  38 .B "#define st_mtine  st_mtim.tv_sec"
  39 .B "#define st_ctime  st_ctim.tv_sec"
  40 .B };
  41 .fi
  42 .PP
  43 .RS -4
  44 Feature Test Macro Requirements for glibc (see
  45 .BR feature_test_macros (7)):
  46 .RE
  47 .PP
  48 .IR st_atim ,
  49 .IR st_mtim ,
  50 .IR st_ctim :
  51 .nf
  52     Since glibc 2.12:
  53         _POSIX_C_SOURCE >= 200809L || _XOPEN_SOURCE >= 700
  54     Glibc 2.19 and earlier:
  55         _BSD_SOURCE || _SVID_SOURCE
  56 .fi
  57 .SH DESCRIPTION
  58 Describes information about a file.
  59 .PP
  60 The fields are as follows:
  61 .TP
  62 .I st_dev
  63 This field describes the device on which this file resides.
  64 (The
  65 .BR major (3)
  66 and
  67 .BR minor (3)
  68 macros may be useful to decompose the device ID in this field.)
  69 .TP
  70 .I st_ino
  71 This field contains the file's inode number.
  72 .TP
  73 .I st_mode
  74 This field contains the file type and mode.
  75 See
  76 .BR inode (7)
  77 for further information.
  78 .TP
  79 .I st_nlink
  80 This field contains the number of hard links to the file.
  81 .TP
  82 .I st_uid
  83 This field contains the user ID of the owner of the file.
  84 .TP
  85 .I st_gid
  86 This field contains the ID of the group owner of the file.
  87 .TP
  88 .I st_rdev
  89 This field describes the device that this file (inode) represents.
  90 .TP
  91 .I st_size
  92 This field gives the size of the file (if it is a regular
  93 file or a symbolic link) in bytes.
  94 The size of a symbolic link is the length of the pathname
  95 it contains, without a terminating null byte.
  96 .TP
  97 .I st_blksize
  98 This field gives the "preferred" block size for efficient filesystem I/O.
  99 .TP
 100 .I st_blocks
 101 This field indicates the number of blocks allocated to the file,
 102 in 512-byte units.
 103 (This may be smaller than
 104 .IR st_size /512
 105 when the file has holes.)
 106 .TP
 107 .I st_atime
 108 This is the time of the last access of file data.
 109 .TP
 110 .I st_mtime
 111 This is the time of last modification of file data.
 112 .TP
 113 .I st_ctime
 114 This is the file's last status change timestamp
 115 (time of last change to the inode).
 116 .PP
 117 For further information on the above fields, see
 118 .BR inode (7).
 119 .SH VERSIONS
 120 Old kernels and old standards did not support nanosecond timestamp fields.
 121 Instead, there were three timestamp
 122 .RI fields\(em st_atime ,
 123 .IR st_mtime ,
 124 and
 125 .IR st_ctime \(emtyped
 126 as
 127 .I time_t
 128 that recorded timestamps with one-second precision.
 129 .PP
 130 Since Linux 2.5.48, the
 131 .I stat
 132 structure supports nanosecond resolution for the three file timestamp fields.
 133 The nanosecond components of each timestamp are available
 134 via names of the form
 135 .IR st_atim.tv_nsec ,
 136 if suitable test macros are defined.
 137 Nanosecond timestamps were standardized in POSIX.1-2008,
 138 and, starting with version 2.12,
 139 glibc exposes the nanosecond component names if
 140 .B _POSIX_C_SOURCE
 141 is defined with the value 200809L or greater, or
 142 .B _XOPEN_SOURCE
 143 is defined with the value 700 or greater.
 144 Up to and including glibc 2.19,
 145 the definitions of the nanoseconds components are also defined if
 146 .B _BSD_SOURCE
 147 or
 148 .B _SVID_SOURCE
 149 is defined.
 150 If none of the aforementioned macros are defined,
 151 then the nanosecond values are exposed with names of the form
 152 .IR st_atimensec .
 153 .SH STANDARDS
 154 POSIX.1-2001 and later.
 155 .SH NOTES
 156 The following header also provides this type:
 157 .IR <ftw.h> .
 158 .SH SEE ALSO
 159 .BR stat (2),
 160 .BR inode (7)