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@(#)ttyname.3 8.1 (Berkeley) 6/4/93
$FreeBSD$
.Dd May 14, 2005 .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 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 The .Fn ttyname_r may fail and return the following error codes: l -tag -width Er t Bq Er ENOTTY The .Fa fd argument is not a valid file descriptor. 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 .