Attach to process

CLion provides a way to attach the debugger to both local and remote processes.

For C/C++ applications, you can attach to a process with GDB or MSVC LLDB on Windows, LLDB on macOS, and both GDB and LLDB on Linux. When applicable, debuggers for other languages (for example, Python debugger) can be used as well.

Prerequisites for Ubuntu

On Ubuntu and some other Linux distributions, you might get the ptrace: Operation not permitted error message upon the first attempt to attach to a process. Do one of the following:

To disable this restriction temporarily, enter the command:
echo 0 | sudo tee /proc/sys/kernel/yama/ptrace_scope
To disable this restriction permanently, open the /etc/sysctl.d/10-ptrace.conf file for editing and change the line kernel.yama.ptrace_scope = 1 to kernel.yama.ptrace_scope = 0.
To apply the changes immediately, enter the above command echo 0 | sudo tee /proc/sys/kernel/yama/ptrace_scope.
Alternatively, run sudo service procps restart or restart your system.

You can find more details here.

Attach to a running process

Press Ctrl+Alt+F5 or select Run | Attach to Process from the main menu.
The Attach to Process dialog opens the list of all the detected running processes.
You can view the processes as a list or as a tree and search for a particular process by name:
For each process, you can find the executable name and process ID, the user that launched it, the available debuggers, and the command used for launching.
Use the drop-down menu to filter the list of processes by the type of the debugger:
You can also filter the list by setting Show only my processes:
The Local tab shows the list of local processes. Select the process and click Attach with....
Switch to the SSH tab to view the list of remote processes. Make sure to configure a remote toolchain with SSH credentials beforehand.
On Windows, switch to the WSL tab to open the list of WSL processes. You will be able to attach to them with the WSL GDB debugger (if you have at least one WSL toolchain configured in your project).
You can attach to processes launched remotely with administrative privileges.
Proceed with debugging the same way you usually do it in CLion (set breakpoints, step through, pause and resume the process, evaluate expressions, and so on).
In case the process you have attached to does not provide debug information, breakpoints will be unavailable and stepping will be performed in the disassembly view.

Attach to an unstarted process

If the process you would like to attach to is not running yet, you can preconfigure attachment using the Attach to an Unstarted Process action:

Set the necessary breakpoints in your code.
Select Run | Attach to an Unstarted Process from the main menu.
In the dialog that opens, specify the command line of the process or an executable name.
To identify the process, CLion will wrap the string you supply in * (asterisks) and use it as a pattern to match against. Often, the executable name alone (e.g. Terminal) is enough. However, you can use * and ? to build patterns. For example, git.exe pu?? origin would match both git.exe push origin and git.exe. pull origin – CLion will attach to the first matching process to start.
Set the Keep the process suspended after attaching checkbox if you would like the process to be paused once CLion attaches to it.
Clear the Reopen dialog after debug checkbox if you do not want CLion to reopen this dialog once the debugging session terminates.
Click Attach and select the debugger (if applicable).

CLion will begin watching. Once it identifies the process, it will automatically attach to it and trigger debugging.

Detach from a process

The procedure of detaching from a remote process is the same as for stopping a debug session. However, note that when you detach, the debug session closes but the process continues to run.

Click the Stop button on the main toolbar in the Debug tool window.
Alternatively, click Stop on the main toolbar or press Ctrl+F2, then select the session to be closed.

22 September 2025