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ttyname(3) Library Functions Manual ttyname(3) NAME ttyname, isatty, ttyname_r - Get the name of a terminal LIBRARY Standard C Library (libc.so, libc.a) SYNOPSIS #include <unistd.h> char *ttyname( int file-descriptor); int isatty( int file-descriptor); int ttyname_r( int file-descriptor, char *buffer, int len); STANDARDS Interfaces documented on this reference page conform to industry stan- dards as follows: ttyname_r(): POSIX.1c isatty(), ttyname(): XPG4, XPG4-UNIX Refer to the standards(5) reference page for more information about in- dustry standards and associated tags. PARAMETERS Specifies an open file descriptor. Points to a buffer in which the terminal name is stored. Specifies the length of the buffer pointed to by the buffer parameter. DESCRIPTION The ttyname() function gets the name of a terminal. It returns a pointer to a string containing the null-terminated pathname of the ter- minal device associated with the file-descriptor parameter. The isatty() function determines if the device associated with the file-descriptor parameter is a terminal. NOTES The ttyname() function returns a pointer to thread-specific data. Sub- sequent calls to this function from the same thread overwrite this data. RETURN VALUES Upon successful completion, the ttyname() function returns a pointer to a string identifying a terminal device. A NULL pointer is returned if the file-descriptor parameter does not describe a terminal device in the /dev directory. Upon successful completion, the isatty() function returns a value of 1 if the specified file-descriptor parameter is associated with a termi- nal. Otherwise, it returns a value of zero (0). [POSIX] Upon successful completion, the ttyname_r() function stores the terminal name as a null-terminated string in the buffer pointed to by the buffer parameter and returns a value of 0 (zero). Otherwise, it returns an error number. [Digital] The obsolete version of ttyname_r() functions the same way as the POSIX version, except it returns a -1 upon unsuccessful comple- tion. ERRORS If the isatty() function fails, errno may be set to the following value: The file associated with file-descriptor is not a terminal. If the ttyname_r() function fails, errno may be set to the following value: The buffer parameter is a null pointer or the len parameter was too short to store the string. RELATED INFORMATION Functions: ttyslot(3) Standards: standards(5) delim off ttyname(3)