如何在 GDB 工具中使用 actions 命令？

Question

Below is the code which i had used to understand actions command in gdb.

#include <stdio.h>
int Use_Action(int CatchedInt, char * CatchedStr)
{
    printf("CatchedInt = %d, CatchedStr = %s\n", CatchedInt, CatchedStr);
    return 0;
}
int main(void)
{
    int PassingInt = 20;
    char PassingStr[10] = "Hello";

    Use_Action(PassingInt, PassingStr);
}

In GDB Tool I have done the following things with the help of https://sourceware.org/gdb/current/onlinedocs/gdb/Tracepoint-Actions.html

(gdb) trace Use_Action 
Tracepoint 1 at 0x1169: file action.c, line 5.
(gdb) info tracepoints 
Num     Type           Disp Enb Address            What
1       tracepoint     keep y   0x0000000000001169 in Use_Action at action.c:5
    not installed on target
(gdb) actions 
Enter actions for tracepoint 1, one per line.
End with a line saying just "end".
>collect CatchedInt
>end
(gdb) info tracepoints 
Num     Type           Disp Enb Address            What
1       tracepoint     keep y   0x0000000000001169 in Use_Action at action.c:5
        collect CatchedInt
    not installed on target

If i had collect the value of "Catchedint" by command collect Catchedint, then how to display the value. Is there something I missed? or i understand this actions command in wrong way!!?

Answer 1

Is there something I missed?

Yes: you need to actually run the program while collecting the trace, using tstart , run and tstop commands.

If you tried that, you would likely get this error:

(gdb) tstart
You can't do that when your target is `exec'

That's because only some targets support tracepoints, and local execution doesn't. You'll need to use gdbserver instead.