Tweak clock_gettime(3) for debug by LD_PRELOAD.
To adjust -1 day the result of clock_gettime(CLOCK_MONOTIME,)
$ cc -shared -o adjust_clock_gettime.so -Wall adjust_clock_gettime.c
$ ADJUST_MONOTIME=-86400 LD_PRELOAD=./adjust_clock_gettime.so PROGRAM
Tweak arc4random(3) for debug by LD_PRELOAD.
To limit 16 bits
$ cc -shared -o tweak_arc4random.so -Wall tweak_arc4random.c
$ TWEAK_ARC4RANDOM_NBITS=16 LD_PRELOAD=./tweak_arc4random.so PROGRAM