getdtablesize(2)

getdtablesize2

Get file descriptor limit

Usage

#include <unistd.h>

int

getdtablesize(void);

Library

Standard C Library (libc, -lc)

Overview

The getdtablesize() system call returns the maximum number of file descriptors that the current process may open. The maximum file descriptor number that the system may assign is the return value minus one. Existing file descriptor numbers may be higher if the limit was lowered after they were opened.

Releases

87 releases since FreeBSD 2.0.5-RELEASE; the text changed 42 times.

  1. 2.0.5–3.3
  2. 3.4
  3. 3.5–3.5.1
  4. 4.0
  5. 4.1–4.3
  6. 4.4
  7. 4.5–4.11
  8. 5.0
  9. 5.1–5.2.1
  10. 5.3–6.3
  11. 6.4
  12. 7.0
  13. 7.1
  14. 7.2
  15. 7.3
  16. 7.4
  17. 8.0
  18. 8.1
  19. 8.2
  20. 8.3
  21. 8.4
  22. 9.0
  23. 9.1
  24. 9.2
  25. 9.3
  26. 10.0
  27. 10.1
  28. 10.2
  29. 10.3
  30. 10.4
  31. 11.0
  32. 11.1
  33. 11.2
  34. 11.3
  35. 11.4
  36. 12.0
  37. 12.1
  38. 12.2
  39. 12.3
  40. 12.4
  41. 13.0–13.2
  42. 13.3–14.5
  43. 15.0–16.0

History

The getdtablesize() system call appeared in 4.2BSD.

From base 16.0-CURRENT-20261027-61c70dc16a79 in FreeBSD 16.0-CURRENT (2026-10-27). Parsed by carta from the page's mdoc source.