{
  "slug": "file-access-time",
  "term": "File access time",
  "aliases": [
    "atime",
    "File access timestamp",
    "Last file access time"
  ],
  "definition": "File access time (atime) is the filesystem timestamp associated with access to a file, subject to the operating system's access-time update policy.",
  "note": "On Linux, reads can update atime, but noatime suppresses access-driven updates and relatime limits them. With relatime, an access updates atime when the previous value is no later than mtime or ctime, or is more than a day old. O_NOATIME can suppress updates for an opened file. [linux-inode] [linux-mount]\n\nlazytime is different: eligible timestamps are updated in memory while persistence may be deferred. Neither an unchanged atime nor delayed on-disk persistence proves that no access occurred. [linux-mount]",
  "related": [
    "inode",
    "file-modification-time",
    "inode-change-time",
    "file-birth-time"
  ],
  "citations": [
    {
      "id": "linux-inode",
      "title": "Linux man-pages: inode(7)",
      "url": "https://man7.org/linux/man-pages/man7/inode.7.html",
      "accessed": "2026-10-21"
    },
    {
      "id": "linux-mount",
      "title": "util-linux: mount(8), access-time policy and lazytime",
      "url": "https://man7.org/linux/man-pages/man8/mount.8.html",
      "accessed": "2026-10-21"
    },
    {
      "id": "linux-utimensat",
      "title": "Linux man-pages: utimensat(2)",
      "url": "https://man7.org/linux/man-pages/man2/utimensat.2.html",
      "accessed": "2026-10-21"
    },
    {
      "id": "hesela-file-times",
      "title": "Hesela: interpreting file timestamps during rsync selection",
      "url": "https://hesela.com/analyses/rsync-delta-shifted-blocks/#file-times",
      "accessed": "2026-10-21"
    }
  ],
  "status": "shipping",
  "advantages": [
    "Can indicate access relative to modification when the applicable update policy is known."
  ],
  "limitations": [
    "May not record every read.",
    "Can be set explicitly and is not a complete access log."
  ],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "updated": "2026-10-21"
}