strace

Use strace (stack trace) to track the system calls that a program makes.
This is typically shown as C code on a Linux system, and shows the system call itself and its output.

strace Usage

To see each of the syscalls a command makes, you can run the command directly after the strace/strace [opts]:

sudo strace mkdir ~/testdir

This is a simple strace call, tracing a mkdir call.
It will only show the system calls made by the mkdir process, not any child processes it may spawn.

If you need to see the strace of the child processes, you can also use the -f or -ff options.

sudo strace -ff mknod -m 666 /tmp/mynull c 1 3

You can also specify the maximum string size with -s (default is 32).

sudo strace -ffs320 mknod -m 666 /tmp/mynull c 1 3