Using opensnoop (with examples)

Tracking all file opens

To track all file opens as they occur on your system, you can simply use the sudo opensnoop command. This will display a real-time log of all file opens, including the process responsible for each open and the path to the file.

Motivation: This can be useful for troubleshooting and debugging purposes. By monitoring file opens, you can identify which processes are accessing specific files and determine if any unexpected or unauthorized file access is occurring.

Example:

sudo opensnoop

Output:

PID    COMM               FD ERR PATH
398    Google Chrome He   23   0 /Users/user/Documents/example.txt
398    Google Chrome He   24   0 /Users/user/Downloads/image.jpg

Tracking all file opens by a process name

If you want to specifically track file opens by a particular process name, you can use the -n option followed by the desired process name. This will only display the file opens performed by processes with the specified name.

Motivation: This can be helpful when you suspect a specific process is responsible for file accesses. By filtering the output to only show file opens by that process, you can easily monitor its file interactions and identify any issues or unexpected behaviors.

Example:

sudo opensnoop -n "process_name"

Output:

PID    COMM               FD ERR PATH
398    process_name      23   0 /path/to/file1
398    process_name      24   0 /path/to/file2

Tracking all file opens by a process PID

If you want to track file opens by a specific process using its Process ID (PID), you can use the -p option followed by the PID. This will only display the file opens performed by the process with the specified PID.

Motivation: Sometimes you may already know the PID of the process you want to monitor. In such cases, using the PID option allows you to specifically track the file opens by that particular process and ignore any other processes that may be accessing files.

Example:

sudo opensnoop -p PID

Output:

PID    COMM               FD ERR PATH
398    process_name      23   0 /path/to/file1
398    process_name      24   0 /path/to/file2

Tracking processes that open a specified file

If you want to determine which processes are opening a specific file, you can use the -f option followed by the path to the file. This will display the processes that have opened the specified file.

Motivation: This can be useful when you want to investigate which processes are accessing a particular file. By monitoring the file opens for that specific file, you can identify the processes responsible and gain insights into how the file is being used.

Example:

sudo opensnoop -f path/to/file

Output:

PID    COMM               FD ERR PATH
398    process1          23   0 /path/to/file
543    process2          12   0 /path/to/file