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 on Windows, LLDB on macOS, and both GDB and LLDB on Linux. When applicable, debuggers for other languages (for example, Python debugger or Swift LLDB) can be used as well.
First off, if you want to debug a program that can be started from CLion, the best way to do it is to start a local debugging session.
Prerequisites for Ubuntu users
If you are using CLion on Ubuntu (or probably, on some other Linux distribution), an error message ptrace: Operation not permitted may appear upon your first attempt to attach to a process. In this case, 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 = 1to
kernel.yama.ptrace_scope = 0.
To apply the changes immediately, enter the above command
echo 0 | sudo tee /proc/sys/kernel/yama/ptrace_scope.
sudo service procps restartor restart your system.
You can find more details here.
Attach to a local process
Press Ctrl+Alt+F5 or choosefrom the main menu.
The list of running local processes is shown. Select the process to attach to.
If necessary, narrow down the list of processes by typing the first letters of its name or PID. If there are several debuggers that can be used for the selected process, you can choose among them in the popup menu:
Note that 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.
Detach from a process
The procedure to detach from a remote process is the same as for stopping a local debug session, however, the effect is different. When you detach, the debugging session closes but the process continues to run.
Click the Stop button on the main toolbar on in the Debug tool window.
Alternatively, click Stop on the main toolbar or press Ctrl+F2, then select the session to be closed.