How to use strace

System Call

System calls are the interface of your operating system. Whether or not you are aware, the app you write is really issuing a number of these system calls to perform different actions: making a http request, writing a csv file etc.

The open system call

To see what files your app is opening: strace -e open cat hello.txt

The write system call

To see what files are being written to: strace -e write echo 'hello' > important.txt

The connection system call

To show every IP your app connects to: strace -e connect

Inbound/outbound network activity

To debug network activity, perhaps a http service strace -e sendto strace -e recvfrom

execve

To find out what cmd is being executed with with args strace -e execve