gdb
Missing separate debuginfos, use: debuginfo-install glibc-2.12-1.149.el6_6.9.x86_64 libgcc-4.4.7-11.el6.x86_64 libstdc++-4.4.7-11.el6.x86_64 zlib-1.2.3-29.el6.x86_64 (gdb) bt #0 0x00007f5de36f6625 in raise () from /lib64/libc.so.6 #1 0x00007f5de36f7e05 in abort () from /lib64/libc.so.6 #2 0x00007f5de4834a7d in __gnu_cxx::__verbose_terminate_handler() () from /usr/lib64/libstdc++.so.6 #3 0x00007f5de4832bd6 in ?? () from /usr/lib64/libstdc++.so.6 #4 0x00007f5de4832c03 in std::terminate() () from /usr/lib64/libstdc++.so.6 #5 0x00007f5de4832c86 in __cxa_rethrow () from /usr/lib64/libstdc++.so.6 #6 0x000000000041817c in SharedPtr<TeacherObj, ReferenceCounter, ReleasePolicy<TeacherObj> >::deref (this=0x7f5ddabfcad0) at /home/diego/work/branch0901_shengwang/rtqa_center/source/..//source/tmbase/utils/include/SharedPtr.h:356 #7 0x00000000004177c0 in SharedPtr<TeacherObj, ReferenceCounter, ReleasePolicy<TeacherObj> >::operator-> (this=0x7f5ddabfcad0) at /home/diego/work/branch0901_shengwang/rtqa_center/source/..//source/tmbase/utils/include/SharedPtr.h:209 #8 0x000000000041e7f6 in CmdTcGetMsp::OnCallBack (this=0x7f5db8000cb0, msg=0x7f5db8002b70) at CmdTeacher.cpp:208 #9 0x000000000040d40a in CommonHandler::OnResponse (this=0x7f5db80043e0, response=...) at BaseMsg.cpp:77 #10 0x000000000040e672 in client::replyhandle (req=0x7f5db8001400, arg=0x7f5db80043e0) at client.cpp:42 #11 0x00007f5de4ec4b41 in evhttp_connection_done (evcon=0x7f5db8000f00) at http.c:817 #12 0x00007f5de4ec5158 in evhttp_read_body (evcon=0x7f5db8000f00, req=0x7f5db8001400) at http.c:964 #13 0x00007f5de4ec5858 in evhttp_get_body (evcon=0x7f5db8000f00, req=0x7f5db8001400) at http.c:1969 #14 0x00007f5de4eb4ee5 in bufferevent_readcb (fd=<value optimized out>, event=<value optimized out>, arg=0x7f5db8001090) at bufferevent_sock.c:186 #15 0x00007f5de4eace0c in event_process_active_single_queue (base=0x1b281a0, flags=0) at event.c:1350 #16 event_process_active (base=0x1b281a0, flags=0) at event.c:1420 #17 event_base_loop (base=0x1b281a0, flags=0) at event.c:1621 #18 0x000000000040e817 in client::httpclient::runeventloop (arg=0x1b281a0) at client.cpp:65 #19 0x00007f5de4a839d1 in start_thread () from /lib64/libpthread.so.0 #20 0x00007f5de37ac8fd in clone () from /lib64/libc.so.6 (gdb) f 8 #8 0x000000000041e7f6 in CmdTcGetMsp::OnCallBack (this=0x7f5db8000cb0, msg=0x7f5db8002b70) at CmdTeacher.cpp:208 208 CmdTeacher.cpp: No such file or directory. in CmdTeacher.cpp (gdb) (gdb) p httpRes $1 = (OrderGetMspRes *) 0x7f5db8002b70 (gdb) p *httpRes $2 = {<HttpRespMsg> = {<BaseMsg> = {_vptr.BaseMsg = 0x51e790, msgType = BaseMsg::OR_GET_MSP, errNo = 0, errMsg = ""}, <No data fields>}, errorMsg = "", statuscode = 1, msp = 4, operId = "shengwang"} (gdb) p st $3 = {_pCounter = 0x7f5db4002b10, _ptr = 0x7f5db4001940} (gdb) p *st Could not find operator*. (gdb) p tc $4 = {_pCounter = 0x7f5dcc0017c0, _ptr = 0x0} (gdb)
我们可以通过 1) gdb prog_name -> r 用在逐步调试自己的程序时
2) gdb -> attach process_id 正在运行中的后台程序突然卡在了某个地方，先ps再gdb/attach
3) gdb prog_name core 程序core掉了
三种方式对一个程序进行调试；
1. thread——gdb 多线程调试命令:
info threads: 显示当前进程中的线程；
thread thread_no: 进入线程xx，通常紧接而来的是 bt/f 命令；
(gdb) info threads 19 Thread 0x7f9024dfa700 (LWP 26847) 0x00007f9038295ef3 in epoll_wait () from /lib64/libc.so.6 18 Thread 0x7f901e1fc700 (LWP 26851) 0x00007f9038259a3d in nanosleep () from /lib64/libc.so.6 17 Thread 0x7f901ffff700 (LWP 26848) 0x00007f9038295ef3 in epoll_wait () from /lib64/libc.so.6 16 Thread 0x7f9035792700 (LWP 26840) 0x00007f9038295ef3 in epoll_wait () from /lib64/libc.so.6 15 Thread 0x7f90261fc700 (LWP 26845) 0x00007f903828c0d3 in poll () from /lib64/libc.so.6 14 Thread 0x7f901f5fe700 (LWP 26849) 0x00007f9038259a3d in nanosleep () from /lib64/libc.so.6 13 Thread 0x7f9027fff700 (LWP 26842) 0x00007f9038259a3d in nanosleep () from /lib64/libc.so.6 12 Thread 0x7f90257fb700 (LWP 26846) 0x00007f90395705bc in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0 11 Thread 0x7f9026bfd700 (LWP 26844) 0x00007f9038259a3d in nanosleep () from /lib64/libc.so.6 10 Thread 0x7f9036b94700 (LWP 26838) 0x00007f903828e373 in select () from /lib64/libc.so.6 9 Thread 0x7f901cdfa700 (LWP 26853) 0x00007f90395705bc in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0 8 Thread 0x7f90275fe700 (LWP 26843) 0x00007f9038259a3d in nanosleep () from /lib64/libc.so.6 7 Thread 0x7f9034d91700 (LWP 26841) 0x00007f9038259a3d in nanosleep () from /lib64/libc.so.6 6 Thread 0x7f9036193700 (LWP 26839) 0x00007f903828e373 in select () from /lib64/libc.so.6 5 Thread 0x7f903a0ec720 (LWP 26827) 0x00007f9038259a3d in nanosleep () from /lib64/libc.so.6 4 Thread 0x7f9037595700 (LWP 26837) 0x00007f9038259a3d in nanosleep () from /lib64/libc.so.6 3 Thread 0x7f901d7fb700 (LWP 26852) 0x00007f903828c0d3 in poll () from /lib64/libc.so.6 2 Thread 0x7f9037f96700 (LWP 26835) 0x00007f9038259a3d in nanosleep () from /lib64/libc.so.6 * 1 Thread 0x7f901ebfd700 (LWP 26850) 0x00007f900c129300 in ?? ()
查看所有线程的调用栈信息
(gdb) thread apply all bt Thread 19 (Thread 0x7f45f72a2700 (LWP 27863)): #0 0x00007f45f7565a3d in nanosleep () from /lib64/libc.so.6 #1 0x00007f45f75658b0 in sleep () from /lib64/libc.so.6 #2 0x00000000005035f8 in TTLogEx::WriteLogThread (ptr=0x0) at TTLogEx.cpp:61 #3 0x0000000000513bbc in Thread::callable_entry (pThread=0x1b82d00) at thread.cpp:125 #4 0x00007f45f887a9d1 in start_thread () from /lib64/libpthread.so.0 #5 0x00007f45f75a18fd in clone () from /lib64/libc.so.6 Thread 18 (Thread 0x7f45f68a1700 (LWP 27865)): #0 0x00007f45f7565a3d in nanosleep () from /lib64/libc.so.6 #1 0x00007f45f75658b0 in sleep () from /lib64/libc.so.6 #2 0x00000000005048e0 in TTLogOp::WriteLogThread (ptr=0x0) at TTLogOp.cpp:62 #3 0x0000000000513bbc in Thread::callable_entry (pThread=0x1b8ac70) at thread.cpp:125 #4 0x00007f45f887a9d1 in start_thread () from /lib64/libpthread.so.0 #5 0x00007f45f75a18fd in clone () from /lib64/libc.so.6 Thread 17 (Thread 0x7f45f5ea0700 (LWP 27866)): #0 0x00007f45f759a373 in select () from /lib64/libc.so.6 #1 0x00007f45f7cf5fbc in SU_sleep (seconds=1, micro_seconds=0) at ../platform/linux/platform.cpp:369 #2 0x00007f45f7cf53c0 in SchedManager::run (this=0x1b88410) at su_sched_manager.cpp:177 #3 0x00007f45f7cf4e6a in run_func (args=0x1b88410) at su_sched_manager.cpp:50 #4 0x00007f45f887a9d1 in start_thread () from /lib64/libpthread.so.0 #5 0x00007f45f75a18fd in clone () from /lib64/libc.so.6 Thread 16 (Thread 0x7f45f549f700 (LWP 27867)): #0 0x00007f45f759a373 in select () from /lib64/libc.so.6 #1 0x00007f45f7cf5e7f in SU_recvfrom (fd=5, addr=0x7f45f549ee30, buf=0x7f45f00008c0, len=1376, ms=5) at ../platform/linux/platform.cpp:340 #2 0x00007f45f7cf26d4 in SchedRPC::run (this=0x1b8a280) at su_sched.cpp:328 #3 0x00007f45f7cf1a27 in rpc_func (args=0x1b8a280) at su_sched.cpp:47 #4 0x00007f45f887a9d1 in start_thread () from /lib64/libpthread.so.0 #5 0x00007f45f75a18fd in clone () from /lib64/libc.so.6 Thread 15 (Thread 0x7f45effff700 (LWP 27868)): #0 0x00007f45f75a1ef3 in epoll_wait () from /lib64/libc.so.6 #1 0x00007f45f8cb5326 in epoll_dispatch (base=0x1b851c0, tv=<value optimized out>) at epoll.c:407 #2 0x00007f45f8ca3ac6 in event_base_loop (base=0x1b851c0, flags=0) at event.c:1607 #3 0x000000000040e9a7 in client::httpclient::runeventloop (arg=0x1b851c0) at client.cpp:65 #4 0x00007f45f887a9d1 in start_thread () from /lib64/libpthread.so.0 ---Type <return> to continue, or q <return> to quit--- #5 0x00007f45f75a18fd in clone () from /lib64/libc.so.6 Thread 14 (Thread 0x7f45ef5fe700 (LWP 27869)): #0 0x00007f45f7565a3d in nanosleep () from /lib64/libc.so.6 #1 0x00007f45f75658b0 in sleep () from /lib64/libc.so.6 #2 0x000000000042d944 in ThreadDistribute (para=0x0) at OrderManager.cpp:1054 #3 0x0000000000513bbc in Thread::callable_entry (pThread=0x1b868d0) at thread.cpp:125 #4 0x00007f45f887a9d1 in start_thread () from /lib64/libpthread.so.0 #5 0x00007f45f75a18fd in clone () from /lib64/libc.so.6 Thread 13 (Thread 0x7f45eebfd700 (LWP 27870)): #0 0x00007f45f7565a3d in nanosleep () from /lib64/libc.so.6 #1 0x00007f45f75658b0 in sleep () from /lib64/libc.so.6 #2 0x000000000042d987 in ThreadTimer (para=0x0) at OrderManager.cpp:1067 #3 0x0000000000513bbc in Thread::callable_entry (pThread=0x1b84b80) at thread.cpp:125 #4 0x00007f45f887a9d1 in start_thread () from /lib64/libpthread.so.0 #5 0x00007f45f75a18fd in clone () from /lib64/libc.so.6 Thread 12 (Thread 0x7f45ee1fc700 (LWP 27871)): #0 0x00007f45f75980d3 in poll () from /lib64/libc.so.6 #1 0x000000000052f6c2 in do_io (v=0x7f45e80018d0) at src/mt_adaptor.c:387 #2 0x00007f45f887a9d1 in start_thread () from /lib64/libpthread.so.0 #3 0x00007f45f75a18fd in clone () from /lib64/libc.so.6 Thread 11 (Thread 0x7f45ed7fb700 (LWP 27872)): #0 0x00007f45f7565a3d in nanosleep () from /lib64/libc.so.6 #1 0x00007f45f75658b0 in sleep () from /lib64/libc.so.6 #2 0x00000000004908a7 in ThreadStudentDelayDel (para=0x0) at StudentManager.cpp:30 #3 0x0000000000513bbc in Thread::callable_entry (pThread=0x1b86e80) at thread.cpp:125 #4 0x00007f45f887a9d1 in start_thread () from /lib64/libpthread.so.0 #5 0x00007f45f75a18fd in clone () from /lib64/libc.so.6 Thread 10 (Thread 0x7f45ecdfa700 (LWP 27873)): #0 0x00007f45f887e5bc in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0 #1 0x000000000052f4ab in do_completion (v=0x7f45e80018d0) at src/mt_adaptor.c:463 #2 0x00007f45f887a9d1 in start_thread () from /lib64/libpthread.so.0 #3 0x00007f45f75a18fd in clone () from /lib64/libc.so.6 Thread 9 (Thread 0x7f45dbfff700 (LWP 27874)): ---Type <return> to continue, or q <return> to quit--- #0 0x00007f45f7565a3d in nanosleep () from /lib64/libc.so.6 #1 0x00007f45f75658b0 in sleep () from /lib64/libc.so.6 #2 0x00000000004e3b81 in ThreadTeacher (para=0x0) at TeacherManager.cpp:29 #3 0x0000000000513bbc in Thread::callable_entry (pThread=0x1b8e390) at thread.cpp:125 #4 0x00007f45f887a9d1 in start_thread () from /lib64/libpthread.so.0 #5 0x00007f45f75a18fd in clone () from /lib64/libc.so.6 Thread 8 (Thread 0x7f45db5fe700 (LWP 27875)): #0 0x00007f45f75a1ef3 in epoll_wait () from /lib64/libc.so.6 #1 0x00007f45f8cb5326 in epoll_dispatch (base=0x1b85820, tv=<value optimized out>) at epoll.c:407 #2 0x00007f45f8ca3ac6 in event_base_loop (base=0x1b85820, flags=0) at event.c:1607 #3 0x000000000051012a in TTLibEvent::RunEventLoop (ptr=0x1b85820) at TTLibEvent.cpp:49 #4 0x0000000000513bbc in Thread::callable_entry (pThread=0x1b857f0) at thread.cpp:125 #5 0x00007f45f887a9d1 in start_thread () from /lib64/libpthread.so.0 #6 0x00007f45f75a18fd in clone () from /lib64/libc.so.6 Thread 7 (Thread 0x7f45dabfd700 (LWP 27876)): #0 0x00007f45f75a1ef3 in epoll_wait () from /lib64/libc.so.6 #1 0x00007f45f8cb5326 in epoll_dispatch (base=0x1b8ca30, tv=<value optimized out>) at epoll.c:407 #2 0x00007f45f8ca3ac6 in event_base_loop (base=0x1b8ca30, flags=0) at event.c:1607 #3 0x000000000051012a in TTLibEvent::RunEventLoop (ptr=0x1b8ca30) at TTLibEvent.cpp:49 #4 0x0000000000513bbc in Thread::callable_entry (pThread=0x1b88ac0) at thread.cpp:125 #5 0x00007f45f887a9d1 in start_thread () from /lib64/libpthread.so.0 #6 0x00007f45f75a18fd in clone () from /lib64/libc.so.6 Thread 6 (Thread 0x7f45da1fc700 (LWP 27877)): #0 0x00007f45f7565a3d in nanosleep () from /lib64/libc.so.6 #1 0x00007f45f759abe4 in usleep () from /lib64/libc.so.6 #2 0x0000000000505c2f in TTWorkThread::run (this=0x1b83cc0) at TTServiceManager.cpp:52 #3 0x0000000000513b12 in Thread::runnable_entry (pThread=0x1b83cc0) at thread.cpp:99 #4 0x00007f45f887a9d1 in start_thread () from /lib64/libpthread.so.0 #5 0x00007f45f75a18fd in clone () from /lib64/libc.so.6 Thread 5 (Thread 0x7f45d97fb700 (LWP 27878)): #0 0x00007f45f7565a3d in nanosleep () from /lib64/libc.so.6 #1 0x00007f45f759abe4 in usleep () from /lib64/libc.so.6 #2 0x0000000000505c2f in TTWorkThread::run (this=0x1b8f5e0) at TTServiceManager.cpp:52 #3 0x0000000000513b12 in Thread::runnable_entry (pThread=0x1b8f5e0) at thread.cpp:99 #4 0x00007f45f887a9d1 in start_thread () from /lib64/libpthread.so.0 ---Type <return> to continue, or q <return> to quit--- #5 0x00007f45f75a18fd in clone () from /lib64/libc.so.6 Thread 4 (Thread 0x7f45d8dfa700 (LWP 27879)): #0 0x00007f45f7565a3d in nanosleep () from /lib64/libc.so.6 #1 0x00007f45f759abe4 in usleep () from /lib64/libc.so.6 #2 0x0000000000505dff in TTServiceManager::RunEventThread (ptr=0x0) at TTServiceManager.cpp:100 #3 0x0000000000513bbc in Thread::callable_entry (pThread=0x1b8f750) at thread.cpp:125 #4 0x00007f45f887a9d1 in start_thread () from /lib64/libpthread.so.0 #5 0x00007f45f75a18fd in clone () from /lib64/libc.so.6 Thread 3 (Thread 0x7f45c3fff700 (LWP 27880)): #0 0x00007f45f75980d3 in poll () from /lib64/libc.so.6 #1 0x000000000052f6c2 in do_io (v=0x1ba0410) at src/mt_adaptor.c:387 #2 0x00007f45f887a9d1 in start_thread () from /lib64/libpthread.so.0 #3 0x00007f45f75a18fd in clone () from /lib64/libc.so.6 Thread 2 (Thread 0x7f45c35fe700 (LWP 27881)): #0 0x00007f45f887e5bc in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0 #1 0x000000000052f4ab in do_completion (v=0x1ba0410) at src/mt_adaptor.c:463 #2 0x00007f45f887a9d1 in start_thread () from /lib64/libpthread.so.0 #3 0x00007f45f75a18fd in clone () from /lib64/libc.so.6 Thread 1 (Thread 0x7f45f93fa720 (LWP 27852)): #0 0x00007f45f7565a3d in nanosleep () from /lib64/libc.so.6 #1 0x00007f45f75658b0 in sleep () from /lib64/libc.so.6 #2 0x0000000000424952 in main (argc=2, argv=0x7fffb45355c8) at main.cpp:166
一、多线程调试 1. 多线程调试,最重要的几个命令: info threads 查看当前进程的线程。 GDB会为每个线程分配一个ID, 后面操作线程的时候会用到这个ID. 前面有*的是当前调试的线程. thread 切换调试的线程为指定ID的线程。 break file.c:100 thread all 在file.c文件第100行处为所有经过这里的线程设置断点。 set scheduler-locking off|on|step 在使用step或者continue命令调试当前被调试线程的时候，其他线程也是同时执行的, 怎么只让被调试程序执行呢？ 通过这个命令就可以实现这个需求。 off 不锁定任何线程，也就是所有线程都执行，这是默认值。 on 只有当前被调试程序会执行。 step 在单步的时候，除了next过一个函数的情况 (熟悉情况的人可能知道，这其实是一个设置断点然后continue的行为)以外， 只有当前线程会执行。 thread apply ID1 ID2 command 让一个或者多个线程执行GDB命令command thread apply all command 让所有被调试线程执行GDB命令command。 2. 使用示例: 线程产生通知：在产生新的线程时, gdb会给出提示信息 (gdb) r Starting program: /root/thread [New Thread 1073951360 (LWP 12900)] [New Thread 1082342592 (LWP 12907)]---以下三个为新产生的线程 [New Thread 1090731072 (LWP 12908)] [New Thread 1099119552 (LWP 12909)] 查看线程：使用info threads可以查看运行的线程。 (gdb) info threads 4 Thread 1099119552 (LWP 12940) 0xffffe002 in ?? () 3 Thread 1090731072 (LWP 12939) 0xffffe002 in ?? () 2 Thread 1082342592 (LWP 12938) 0xffffe002 in ?? () * 1 Thread 1073951360 (LWP 12931) main (argc=1, argv=0xbfffda04) at thread.c:21 (gdb) 注意，行首为gdb分配的线程ID号，对线程进行切换时，使用该ID号码。 另外，行首的星号标识了当前活动的线程 切换线程： 使用 thread THREADNUMBER 进行切换，THREADNUMBER 为上文提到的线程ID号。 下例显示将活动线程从 1 切换至 4。 (gdb) info threads 4 Thread 1099119552 (LWP 12940) 0xffffe002 in ?? () 3 Thread 1090731072 (LWP 12939) 0xffffe002 in ?? () 2 Thread 1082342592 (LWP 12938) 0xffffe002 in ?? () * 1 Thread 1073951360 (LWP 12931) main (argc=1, argv=0xbfffda04) at thread.c:21 (gdb) thread 4 [Switching to thread 4 (Thread 1099119552 (LWP 12940))]#0 0xffffe002 in ?? () (gdb) info threads * 4 Thread 1099119552 (LWP 12940) 0xffffe002 in ?? () 3 Thread 1090731072 (LWP 12939) 0xffffe002 in ?? () 2 Thread 1082342592 (LWP 12938) 0xffffe002 in ?? () 1 Thread 1073951360 (LWP 12931) main (argc=1, argv=0xbfffda04) at thread.c:21 (gdb) 以上即为使用gdb提供的对多线程进行调试的一些基本命令。 另外，gdb也提供对线程的断点设置以及对指定或所有线程发布命令的命令 二、调试宏 在GDB下, 我们无法print宏定义，因为宏是预编译的。 但是我们还是有办法来调试宏，这个需要GCC的配合。 在GCC编译程序的时候，加上 -ggdb3 参数，这样，你就可以调试宏了。 另外，你可以使用下述的GDB的宏调试命令 来查看相关的宏。 info macro 查看这个宏在哪些文件里被引用了，以及宏定义是什么样的。 macro 查看宏展开的样子。 三、源文件 GDB时,提示找不到源文件。 需要做下面的检查: 编译程序员是否加上了 -g参数 以包含debug信息。 路径是否设置正确了。 使用GDB的directory命令来设置源文件的目录。 下面给一个调试/bin/ls的示例(ubuntu下) $ apt-get source coreutils $ sudo apt-get install coreutils-dbgsym $ gdb /bin/ls GNU gdb (GDB) 7.1-ubuntu (gdb) list main 1192 ls.c: No such file or directory. in ls.c (gdb) directory ~/src/coreutils-7.4/src/ Source directories searched: /home/hchen/src/coreutils-7.4:$cdir:$cwd (gdb) list main 1192 } 1193 } 1194 1195 int 1196 main (int argc, char **argv) 1197 { 1198 int i; 1199 struct pending *thispend; 1200 int n_files; 1201 四、条件断点 条件断点是语法是： break [where] if [condition] 这种断点真是非常管用。 尤其是在一个循环或递归中，或是要监视某个变量。 注意，这个设置是在GDB中的，只不过每经过那个断点时GDB会帮你检查一下条件是否满足。 五、命令行参数 有时候，我们需要调试的程序需要有命令行参数, 有三种方法： gdb命令行的 -args 参数 gdb环境中 set args命令。 gdb环境中 run 参数 六、gdb的变量 有时候，在调试程序时，我们不单单只是查看运行时的变量， 我们还可以直接设置程序中的变量，以模拟一些很难在测试中出现的情况，比较一些出错， 或是switch的分支语句。使用set命令可以修改程序中的变量。 另外，你知道gdb中也可以有变量吗？ 就像shell一样，gdb中的变量以$开头，比如你想打印一个数组中的个个元素，你可以这样： (gdb) set $i = 0 (gdb) p a[$i++] ... #然后就一路回车下去了 当然，这里只是给一个示例，表示程序的变量和gdb的变量是可以交互的。 七、x命令 也许，你很喜欢用p命令。 所以，当你不知道变量名的时候，你可能会手足无措，因为p命令总是需要一个变量名的。 x命令是用来查看内存的，在gdb中 “help x” 你可以查看其帮助。 x/x 以十六进制输出 x/d 以十进制输出 x/c 以单字符输出 x/i 反汇编 – 通常，我们会使用 x/10i $ip-20 来查看当前的汇编（$ip是指令寄存器） x/s 以字符串输出 八、command命令 如何自动化调试。 这里向大家介绍command命令，简单的理解一下，其就是把一组gdb的命令打包，有点像字处理软件的“宏”。 下面是一个示例： (gdb) break func Breakpoint 1 at 0x3475678: file test.c, line 12. (gdb) command 1 Type commands for when breakpoint 1 is hit, one per line. End with a line saying just "end". >print arg1 >print arg2 >print arg3 >end (gdb) 当我们的断点到达时，自动执行command中的三个命令，把func的三个参数值打出来。
使用gdb ctrl 是有时候会报错，找不到相应的so文件，这个时候可以这样做
1 编辑/etc/ld.so.conf 文件，将so所在的位置加到/etc/ld.so.conf文件中。
2 ldconfig ，使之生效。
ldconfig是一个动态链接库管理命令
为了让动态链接库为系统所共享,还需运行动态链接库的管理命令--ldconfig
ldconfig 命令的用途,主要是在默认搜寻目录(/lib和/usr/lib)以及动态库配置文件/etc/ld.so.conf内所列的目录下,搜索出可共享的动态 链接库(格式如前介绍,lib*.so*),进而创建出动态装入程序(ld.so)所需的连接和缓存文件.缓存文件默认为 /etc/ld.so.cache,此文件保存已排好序的动态链接库名字列表.
ldconfig通常在系统启动时运行,而当用户安装了一个新的动态链接库时,就需要手工运行这个命令.
