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ISATTY(3) Linux Programmer's Manual ISATTY(3)
isatty - test whether a file descriptor refers to a terminal
#include <unistd.h> int isatty(int fd);
The isatty() function tests whether fd is an open file descriptor referring to a terminal.
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.
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).
For an explanation of the terms used in this section, see attributes(7). ┌──────────────────────────────────────┬───────────────┬─────────┐ │Interface │ Attribute │ Value │ ├──────────────────────────────────────┼───────────────┼─────────┤ │isatty() │ Thread safety │ MT-Safe │ └──────────────────────────────────────┴───────────────┴─────────┘
POSIX.1-2001, POSIX.1-2008, SVr4, 4.3BSD.
fstat(2), ttyname(3)
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Linux 2021-03-22 ISATTY(3)
Pages that refer to this page: bash(1), ttyname(3)
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