isatty(3) — Linux manual page

 isatty(3) Library Functions Manual isatty(3) 

NAME         top

 isatty - test whether a file descriptor refers to a terminal 

LIBRARY         top

 Standard C library (libc, -lc) 

SYNOPSIS         top

 #include <unistd.h> int isatty(int fd); 

DESCRIPTION         top

 The isatty() function tests whether fd is an open file descriptor referring to a terminal. 

RETURN VALUE         top

 isatty() returns 1 if fd is an open file descriptor referring to a terminal; otherwise 0 is returned, and errno is set to indicate the error. 

ERRORS         top

 EBADF fd is not a valid file descriptor. ENOTTY fd refers to a file other than a terminal. On some older kernels, some types of files resulted in the error EINVAL in this case (which is a violation of POSIX, which specifies the error ENOTTY). 

ATTRIBUTES         top

 For an explanation of the terms used in this section, see attributes(7). ┌──────────────────────────────────────┬───────────────┬─────────┐ │ Interface │ Attribute │ Value │ ├──────────────────────────────────────┼───────────────┼─────────┤ │ isatty() │ Thread safety │ MT-Safe │ └──────────────────────────────────────┴───────────────┴─────────┘ 

STANDARDS         top

 POSIX.1-2008. 

HISTORY         top

 POSIX.1-2001, SVr4, 4.3BSD. 

SEE ALSO         top

 fstat(2), ttyname(3) 

COLOPHON         top

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Pages that refer to this page: bash(1),  ttyname(3)

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