SAS/C Library Reference, Vol. 1

ctermid -- Get Filename for the Terminal

SYNOPSIS

 #include <lcio.h>

 char *ctermid(char *termid);

The synopsis for the POSIX implementation is as follows:

 #include <unistd.h>

 char *ctermid(char *termid);

This set of header files requires the definition of an appropriate feature test macro. See Feature Test Macros for more information.

DESCRIPTION

ctermid returns the filename of the user's terminal. string is the terminal filename.

The argument to ctermid should be NULL, or it should address a character array (termid) whose size is at least L_ctermid. The symbol L_ctermid is defined in the header file <lcio.h> (or <stdio.h> if an appropriate feature test macro is defined).

If the argument is not NULL, the filename (followed by '\0') is copied into the area addressed by termid. If the argument is NULL, the filename can only be accessed by using the value returned by ctermid.

RETURN VALUE

The return value is a pointer to the filename. If the argument to ctermid is NULL (the norm), the return value is in static storage and may be overlaid by the next call to ctermid.

CAUTION

If a noninteractive program calls ctermid, an attempt to open the filename returned by ctermid may fail.

EXAMPLE

This example sends a message to a terminal:

  #include <lcio.h>

  main()
  {
        /* Open the terminal for writing.                   */
     FILE *termfile;

        /* Assign name of interactive terminal to termfile. */
     termfile = fopen(ctermid(NULL), "w");

     if (!termfile) {
        printf("File could not be opened.n", stderr);
        exit(1);
     }

        /* Print message to interactive terminal.           */
     fprintf(termfile, "This is a test message.n");
     fclose(termfile);
  }

RELATED FUNCTIONS

ttyname