How to make a process in T (trace) state in Linux?

Question

According to What does the “interruptible sleep” state indicate? there is a state called "T".

I tried to run a python script with strace but /proc/pid/stat still showed the the process was in S, waiting on do_wait (cat /proc/6145/wchan -> do_wait)

def f():
    import pdb
    pdb.set_trace()
    print(1)

f()

T state means the process is being traced, not tracing others — 炸鱼薯条德里克, Aug 12 '19 at 23:40
@炸鱼薯条德里克I tried looking at `stat` of the program being traced (python script), still under `S`. Not `T`. — CppLearner, Aug 12 '19 at 23:43

score 3 · Accepted Answer · answered Aug 12 '19 at 23:52

3

You seem to have T mixed up with t. From man ps:

               T    stopped by job control signal
               t    stopped by debugger during the tracing

Anyway, to put a process in state T (stopped), kill -STOP its PID, or hit Ctrl+Z while it's running in the terminal. To put a process in state t (being traced), attach to it with ptrace, but don't let it continue like strace does. One way to do this is run gdb, then attach to its PID.

answered Aug 12 '19 at 23:52

Joseph Sible-Reinstate Monica

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strace is using `PTRACE_SEIZE`, and simply `gdb -p PID` will work. – Aug 13 '19 at 01:44
Thank you very much!! – CppLearner Aug 13 '19 at 23:40

How to make a process in T (trace) state in Linux?

1 Answers1