END(3) BSD Library Functions Manual END(3)NAME
end, etext, edata -- end boundaries of image segments
The globals end, etext and edata are program segment end addresses.
etext is the first address after the end of the text segment.
edata is the first address after the end of the initialized data segment.
end is the first address after the end of the data segment (BSS) when the program is loaded. Use the sbrk(2) system call with zero as its
argument to find the current end of the data segment.
SEE ALSO sbrk(2), malloc(3), a.out(5)HISTORY
An end manual page appeared in Version 6 AT&T UNIX.
Traditionally, no variable existed that pointed to the start of the text segment because the text segment always started at address zero.
Although it is no longer valid to make this assumption, no variable similar to the ones documented above exists to point to the start of the
BSD August 28, 2000 BSD
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END(3) Linux Programmer's Manual END(3)NAME
etext, edata, end - end of program segments
The addresses of these symbols indicate the end of various program segments:
etext This is the first address past the end of the text segment (the program code).
edata This is the first address past the end of the initialized data segment.
end This is the first address past the end of the uninitialized data segment (also known as the BSS segment).
Although these symbols have long been provided on most UNIX systems, they are not standardized; use with caution.
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.
When run, the program below produces output such as the following:
First address past:
program text (etext) 0x8048568
initialized data (edata) 0x804a01c
uninitialized data (end) 0x804a024
extern char etext, edata, end; /* The symbols must have some type,
or "gcc -Wall" complains */
main(int argc, char *argv)
printf("First address past:
printf(" program text (etext) %10p
printf(" initialized data (edata) %10p
printf(" uninitialized data (end) %10p
SEE ALSO objdump(1), readelf(1), sbrk(2), elf(5)COLOPHON
This page is part of release 3.53 of the Linux man-pages project. A description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
GNU 2008-07-17 END(3)