1 This should demonstrate the use of LD_PRELOAD.

     2 

     3     hallo:	uses virgin puts(3) and readdir(3)

     4     myhallo:	uses modified puts(3) and readdir(3)

     5 

     6 If you set the environment 

     7 

     8     LD_PRELOAD=`pwd`/libmy.so.1.0.1

     9 

    10 the "hallo" should use the modified versions of the above

    11 funtions too.

    12 

    13 The modification is visibable, as puts(3) prints an

    14 extra string before the real output, and readdir(3) skips

    15 any directory entry starting with 'M'.

    16 

    17 No considerations done about race conditions and other nice things.

    18 It is just an nice example…

    19 

    20 -- 

    21 Heiko Schlittermann