Tracing BSD System Calls

Tracing BSD System Calls

By Sean Eric Fagan

Dr. Dobb's Journal March 1998

garth% truss echo "Hello, World"
    returns 0x0 (0)
SYSCALL fstat
 0x1 0xefbfd7ec
    returns 0x0 (0)
SYSCALL readlink
 0x6cac 0xefbfd7d8 0x3f
    errno 2 'No such file or directory'
SYSCALL __syscall
 0xc5 0x0 0x0 0x1000 0x3 0x1002 0xffffffff 0x0
    returns 0x8009000 (134254592)
SYSCALL break
 0xc000
    returns 0x0 (0)
SYSCALL break
 0xe000
    returns 0x0 (0)
SYSCALL write
 0x1 0xc000 0xd
Hello, World
    returns 0xd (13)
SYSCALL exit
 0x0
process exit, rval = 0

Example 1: Sample output of truss.