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unlocked_stdio(3) — Linux manual page

unlocked_stdio(3)        Library Functions Manualunlocked_stdio(3)

NAME        top

       getc_unlocked, getchar_unlocked, putc_unlocked, putchar_unlocked -       nonlocking stdio functions

LIBRARY        top

       Standard C library (libc,-lc)

SYNOPSIS        top

#include <stdio.h>int getc_unlocked(FILE *stream);int getchar_unlocked(void);int putc_unlocked(intc, FILE *stream);int putchar_unlocked(intc);void clearerr_unlocked(FILE *stream);int feof_unlocked(FILE *stream);int ferror_unlocked(FILE *stream);int fileno_unlocked(FILE *stream);int fflush_unlocked(FILE *_Nullablestream);int fgetc_unlocked(FILE *stream);int fputc_unlocked(intc, FILE *stream);size_t fread_unlocked(size_t size, size_t n;voidptr[restrictsize*n],size_tsize, size_tn,FILE *restrictstream);size_t fwrite_unlocked(size_t size, size_t n;const voidptr[restrictsize*n],size_tsize, size_tn,FILE *restrictstream);char *fgets_unlocked(int n;chars[restrictn], intn, FILE *restrictstream);int fputs_unlocked(const char *restricts, FILE *restrictstream);#include <wchar.h>wint_t getwc_unlocked(FILE *stream);wint_t getwchar_unlocked(void);wint_t fgetwc_unlocked(FILE *stream);wint_t fputwc_unlocked(wchar_twc, FILE *stream);wint_t putwc_unlocked(wchar_twc, FILE *stream);wint_t putwchar_unlocked(wchar_twc);wchar_t *fgetws_unlocked(int n;wchar_tws[restrictn], intn,FILE *restrictstream);int fputws_unlocked(const wchar_t *restrictws,FILE *restrictstream);   Feature Test Macro Requirements for glibc (seefeature_test_macros(7)):getc_unlocked(),getchar_unlocked(),putc_unlocked(),putchar_unlocked():           /* glibc >= 2.24: */ _POSIX_C_SOURCE >= 199309L               || /* glibc <= 2.23: */ _POSIX_C_SOURCE               || /* glibc <= 2.19: */ _SVID_SOURCE || _BSD_SOURCEclearerr_unlocked(),feof_unlocked(),ferror_unlocked(),fileno_unlocked(),fflush_unlocked(),fgetc_unlocked(),fputc_unlocked(),fread_unlocked(),fwrite_unlocked():           /* glibc >= 2.19: */ _DEFAULT_SOURCE               || /* glibc <= 2.19: */ _SVID_SOURCE || _BSD_SOURCEfgets_unlocked(),fputs_unlocked(),getwc_unlocked(),getwchar_unlocked(),fgetwc_unlocked(),fputwc_unlocked(),putwchar_unlocked(),fgetws_unlocked(),fputws_unlocked():           _GNU_SOURCE

DESCRIPTION        top

       Each of these functions has the same behavior as its counterpart       without the "_unlocked" suffix, except that they do not use       locking (they do not set locks themselves, and do not test for the       presence of locks set by others) and hence are thread-unsafe.  Seeflockfile(3).

ATTRIBUTES        top

       For an explanation of the terms used in this section, seeattributes(7).       ┌──────────────────────┬───────────────┬─────────────────────────┐       │Interface│Attribute│Value│       ├──────────────────────┼───────────────┼─────────────────────────┤       │getc_unlocked(),     │ Thread safety │ MT-Safe race:stream     │       │putc_unlocked(),     │               │                         │       │clearerr_unlocked(), │               │                         │       │fflush_unlocked(),   │               │                         │       │fgetc_unlocked(),    │               │                         │       │fputc_unlocked(),    │               │                         │       │fread_unlocked(),    │               │                         │       │fwrite_unlocked(),   │               │                         │       │fgets_unlocked(),    │               │                         │       │fputs_unlocked(),    │               │                         │       │getwc_unlocked(),    │               │                         │       │fgetwc_unlocked(),   │               │                         │       │fputwc_unlocked(),   │               │                         │       │putwc_unlocked(),    │               │                         │       │fgetws_unlocked(),   │               │                         │       │fputws_unlocked()    │               │                         │       ├──────────────────────┼───────────────┼─────────────────────────┤       │getchar_unlocked(),  │ Thread safety │ MT-Unsafe race:stdin    │       │getwchar_unlocked()  │               │                         │       ├──────────────────────┼───────────────┼─────────────────────────┤       │putchar_unlocked(),  │ Thread safety │ MT-Unsafe race:stdout   │       │putwchar_unlocked()  │               │                         │       ├──────────────────────┼───────────────┼─────────────────────────┤       │feof_unlocked(),     │ Thread safety │ MT-Safe                 │       │ferror_unlocked(),   │               │                         │       │fileno_unlocked()    │               │                         │       └──────────────────────┴───────────────┴─────────────────────────┘

STANDARDS        top

getc_unlocked()getchar_unlocked()putc_unlocked()putchar_unlocked()              POSIX.1-2008.       Others:              None.

HISTORY        top

getc_unlocked()getchar_unlocked()putc_unlocked()putchar_unlocked()              POSIX.1-2001.

SEE ALSO        top

flockfile(3),stdio(3)

COLOPHON        top

       This page is part of theman-pages (Linux kernel and C library       user-space interface documentation) project.  Information about       the project can be found at        ⟨https://www.kernel.org/doc/man-pages/⟩.  If you have a bug report       for this manual page, see       ⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.       This page was obtained from the tarball man-pages-6.15.tar.gz       fetched from       ⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on       2025-08-11.  If you discover any rendering problems in this HTML       version of the page, or you believe there is a better or more up-       to-date source for the page, or you have corrections or       improvements to the information in this COLOPHON (which isnot       part of the original manual page), send a mail to       man-pages@man7.orgLinux man-pages 6.15            2025-06-28unlocked_stdio(3)

Pages that refer to this page:ferror(3), fflush(3), fgetc(3), fgetwc(3), fgetws(3), fileno(3), flockfile(3), fputwc(3), fputws(3), fread(3), gets(3), getwchar(3), puts(3), putwchar(3), stdio(3)

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