execsnoop - macOS

Overview

execsnoop is a diagnostic command-line tool available on macOS that monitors and logs process execution in real time. Primarily used for debugging and security auditing, it traces system-wide process creation, showing which command was executed, by whom, and when. This tool is most effective in environments where understanding or capturing the invocation of new processes is critical, such as in system troubleshooting or monitoring for unauthorized activities.

Syntax

execsnoop [-a] [-A] [-n] [-v] [-t] [-x] [-q] [-T]

The command does not require any positional parameters, but options can be set to refine its output or alter its behavior.

Options/Flags

-a: Displays the command-line arguments for each executed process.
-A: Only shows processes that are already running when execsnoop starts. This is useful for focusing on existing processes rather than newly invoked ones.
-n: Suppresses the column header making the output more suitable for parsing by other scripts or tools.
-v: Enables verbose output, providing additional details about each process event.
-t: Includes a timestamp with each event, helping with chronological tracing of process creation.
-x: Shows extended information, including environment variables used when executing the process.
-q: Quiet mode – suppress the output of the command itself, reducing clutter in the logs.
-T: Outputs events with high-resolution timestamps, where supported, for more granular time tracking.

Examples

Basic Usage: Monitor all executed processes on your system.
```
execsnoop
```
Verbose and Timestamped Output: Get detailed logs, including timestamps.
```
execsnoop -v -t
```
Filtering Existing Processes: Track only existing processes from the point of execution.
```
execsnoop -A
```
Silent Execution with Arguments:
Capture process execution silently but include command-line arguments.
```
execsnoop -q -a
```

Common Issues

Performance Impact: Continuous use of execsnoop, especially with verbose or extended output, can impact system performance due to the high volume of logged data.
Solution: Use selectively or during off-peak hours.
Incomplete Output: Some commands might invoke subprocesses that execsnoop doesn’t log if missing appropriate privileges.
Tip: Run execsnoop with elevated permissions using sudo to capture more comprehensive data.

Integration

Combine execsnoop with other commands to automate monitoring or processing:

execsnoop -t | grep 'specific_process' >> /var/log/specific_process.log

This example monitors for ‘specific_process’, logs events with timestamps, and appends them to a log file, which could be periodically reviewed or processed further.

dtruss: Monitors syscall activity, similar in spirit to execsnoop but at a lower system level.
opensnoop: Logs file access events, useful for debugging file access issues in tandem with process execution.

For more in-depth exploration, refer to documentation provided by the Apple Developer resource pages, which contain manuals and references for these diagnostic tools.