The Linux Development Platform Configuring, Using, and ... - Classes

CH07.fm Page 238 Monday, October 7, 2002 9:12 PM
238 Chapter 7 • Miscellaneous Tools
2 main()
3 {
4 printf ("Hello world\n");
5 }
Now you can display the line number of the source code file corresponding to address
8048466 in the object file with the following command:
[root@boota]# addr2line -e a.out 8048466
/root/chap-07/ltrace/a.c:4
[root@boota]#
This is the line where the printf function is called in a.c file. The add2line command
is useful in debuggers where you need to map addresses to a line in source code file.
7.8 Using the ldd Utility
The ldd utility is very useful in finding out the dependencies of an executable on shared libraries.
This is necessary when you are copying executable files from one computer to another to
make sure that required libraries are present on the destination computer also. The following
command shows that libc.so.6 must be present to execute a.out file on a computer.
[root@boota]# ldd a.out
libc.so.6 => /lib/i686/libc.so.6 (0x4002c000)
/lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
[root@boota]#
So if you copy a.out to another computer, make sure that this library is also present on
the destination computer.
7.9 References and Resources
1. GNU web site at http://www.gnu.org/
2. The cbrowser home page at http://cbrowser.sourceforge.net
3. The cscope home page at http://cscope.sourceforge.net