end(3) | Library Functions Manual | end(3) |
NAME¶
etext, edata, end - end of program segments
SYNOPSIS¶
extern etext; extern edata; extern end;
DESCRIPTION¶
The addresses of these symbols indicate the end of various program segments:
STANDARDS¶
Although these symbols have long been provided on most UNIX systems, they are not standardized; use with caution.
NOTES¶
The program must explicitly declare these symbols; they are not defined in any header file.
On some systems the names of these symbols are preceded by underscores, thus: _etext, _edata, and _end. These symbols are also defined for programs compiled on Linux.
At the start of program execution, the program break will be somewhere near &end (perhaps at the start of the following page). However, the break will change as memory is allocated via brk(2) or malloc(3). Use sbrk(2) with an argument of zero to find the current value of the program break.
EXAMPLES¶
When run, the program below produces output such as the following:
$ ./a.out First address past:
program text (etext) 0x8048568
initialized data (edata) 0x804a01c
uninitialized data (end) 0x804a024
Program source¶
#include <stdio.h> #include <stdlib.h> extern char etext, edata, end; /* The symbols must have some type,
or "gcc -Wall" complains */ int main(void) {
printf("First address past:\n");
printf(" program text (etext) %10p\n", &etext);
printf(" initialized data (edata) %10p\n", &edata);
printf(" uninitialized data (end) %10p\n", &end);
exit(EXIT_SUCCESS); }
SEE ALSO¶
2022-10-30 | Linux man-pages 6.03 |