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# EXC_CRASH (SIGSYS)

A bad argument to a system call terminated the process.

## Discussion

System calls are low-level interfaces
that ask the operating system to perform an action.
This signal indicates that the requested system call doesn’t exist.

For example,
the code below uses system call number 12345,
which isn’t valid and produces a `SIGSYS` signal.

```c
#include <unistd.h>

int main(int argc, char **argv) {
    syscall(12345);
    return 0;
}
```

For a list of valid system calls, see the `syscall.h` header file.

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