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@(#)ttyname.3 8.1 (Berkeley) 6/4/93
$FreeBSD: releng/10.2/lib/libc/gen/ttyname.3 278417 2015-02-08 22:29:06Z jilles $
.Dd July 18, 2014 .Dt TTYNAME 3 .Os .Sh NAME .Nm ttyname , .Nm ttyname_r , .Nm isatty .Nd get name of associated terminal (tty) from file descriptor .Sh LIBRARY .Lb libc .Sh SYNOPSIS n unistd.h .Ft char * .Fn ttyname "int fd" .Ft int .Fn ttyname_r "int fd" "char *buf" "size_t len" .Ft int .Fn isatty "int fd" .Sh DESCRIPTION These functions operate on file descriptors for terminal type devices.
p The .Fn isatty function determines if the file descriptor .Fa fd refers to a valid terminal type device.
p The .Fn ttyname function gets the related device name of a file descriptor for which .Fn isatty is true.
p The .Fn ttyname function returns the name stored in a static buffer which will be overwritten on subsequent calls. The .Fn ttyname_r function takes a buffer and length as arguments to avoid this problem. .Sh RETURN VALUES The .Fn isatty function returns 1 if .Fa fd refers to a terminal type device; otherwise, it returns 0 and may set .Va errno to indicate the error. The .Fn ttyname function returns the null terminated name if the device is found and .Fn isatty is true; otherwise a .Dv NULL pointer is returned. The .Fn ttyname_r function returns 0 if successful. Otherwise an error number is returned. .Sh ERRORS These functions may fail if: l -tag -width Er t Bq Er EBADF The .Fa fd argument is not a valid file descriptor. t Bq Er ENOTTY The file associated with .Fa fd is not a terminal. .El
p Additionally, .Fn ttyname_r may fail if: l -tag -width Er t Bq Er ERANGE The .Fa bufsize argument is smaller than the length of the string to be returned. .El .Sh SEE ALSO .Xr fdevname 3 , .Xr ptsname 3 , .Xr tcgetattr 3 , .Xr tty 4 .Sh HISTORY The .Fn isatty and .Fn ttyname functions appeared in .At v7 . The .Fn ttyname_r function appeared in .Fx 6.0 .