# 调试已经运行的进程 ## 例子 #include <stdio.h> #include <pthread.h> void *thread_func(void *p_arg) { while (1) { printf("%s\n", (char*)p_arg); sleep(10); } } int main(void) { pthread_t t1, t2; pthread_create(&t1, NULL, thread_func, "Thread 1"); pthread_create(&t2, NULL, thread_func, "Thread 2"); sleep(1000); return; } ## 技巧 调试已经运行的进程有两种方法：一种是gdb启动时，指定进程的ID：gdb program processID（也可以用-p或者--pid指定进程ID，例如：gdb program -p=10210）。以上面代码为例，用“ps”命令已经获得进程ID为10210： bash-3.2# gdb -q a 10210 Reading symbols from /data/nan/a...done. Attaching to program `/data/nan/a', process 10210 [New process 10210] Retry #1: Retry #2: Retry #3: Retry #4: Reading symbols from /usr/lib/libc.so.1...(no debugging symbols found)...done. [Thread debugging using libthread_db enabled] [New LWP 3 ] [New LWP 2 ] [New Thread 1 (LWP 1)] [New Thread 2 (LWP 2)] [New Thread 3 (LWP 3)] Loaded symbols for /usr/lib/libc.so.1 Reading symbols from /lib/ld.so.1...(no debugging symbols found)...done. Loaded symbols for /lib/ld.so.1 [Switching to Thread 1 (LWP 1)] 0xfeeeae55 in ___nanosleep () from /usr/lib/libc.so.1 (gdb) bt #0 0xfeeeae55 in ___nanosleep () from /usr/lib/libc.so.1 #1 0xfeedcae4 in sleep () from /usr/lib/libc.so.1 #2 0x080509ef in main () at a.c:17 如果嫌每次ps查看进程号比较麻烦，请尝试如下脚本 ```shell # 保存为xgdb.sh（添加可执行权限） # 用法 xgdb.sh a prog_bin=$1 running_name=$(basename $prog_bin) pid=$(/sbin/pidof $running_name) gdb attach $pid ``` 另一种是先启动gdb，然后用“attach”命令“附着”在进程上： bash-3.2# gdb -q a Reading symbols from /data/nan/a...done. (gdb) attach 10210 Attaching to program `/data/nan/a', process 10210 [New process 10210] Retry #1: Retry #2: Retry #3: Retry #4: Reading symbols from /usr/lib/libc.so.1...(no debugging symbols found)...done. [Thread debugging using libthread_db enabled] [New LWP 3 ] [New LWP 2 ] [New Thread 1 (LWP 1)] [New Thread 2 (LWP 2)] [New Thread 3 (LWP 3)] Loaded symbols for /usr/lib/libc.so.1 Reading symbols from /lib/ld.so.1...(no debugging symbols found)...done. Loaded symbols for /lib/ld.so.1 [Switching to Thread 1 (LWP 1)] 0xfeeeae55 in ___nanosleep () from /usr/lib/libc.so.1 (gdb) bt #0 0xfeeeae55 in ___nanosleep () from /usr/lib/libc.so.1 #1 0xfeedcae4 in sleep () from /usr/lib/libc.so.1 #2 0x080509ef in main () at a.c:17 如果不想继续调试了，可以用“detach”命令“脱离”进程： (gdb) detach Detaching from program: /data/nan/a, process 10210 (gdb) bt No stack. 详情参见[gdb手册](https://sourceware.org/gdb/current/onlinedocs/gdb/Attach.html#index-attach) ## 贡献者 nanxiao