UNIX & GNU/Linux - System calls - Using tgetent()

The tgetent() function is a Linux system call function. It is designed to be used with other termcap functions such as:

• tgetflag
• tgetnum
• tgetstr
• tgoto
• tputs

With the tgetent() function, we stock in the first parameter (a buffer pointer), the capabilities of the second parameter (the environment variable retrieved by the getenv() function).
This function returns 1 on success, 0 if there is not a such description and -1 if the terminfo database is not found.

Let’s see an example of the tgetent() function with the “TERM” variable and its height and width:

/*
** Made by BadproG.com
*/

#include        <stdio.h>
#include        <curses.h>
#include        <term.h>
#include        <stdlib.h>

int     main()
{
  const char *name;
  char  *bp;
  char  *term;
  int   height;
  int   width;
  bp = malloc(sizeof(*bp));
  name = "TERM";
  if ((term = getenv(name)) == NULL)
    return (1);
  printf("My terminal is %s.\n", term);
  tgetent(bp, term);
  height = tgetnum ("li");
  width = tgetnum ("co");
  printf("H : %d\nL : %d\n", height, width);
  free(bp);
  return (0);
}

Do not forget to use the -lncurses library when you compile. Note that you can use the -ltermcap library as well:

$ cc main.c -lncurses

and

$ ./a.out