# 調試已經運行的進程 ## 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 調試已經運行的進程有兩種方法：一種是gdb啟動時，指定進程的ID：gdb program processID（也可以用-p或者--pid指定進程ID，例如：gdb program -p=10210）。以上面代碼為例，用“ps”命令已經獲得進程ID為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查看進程號比較麻煩，請嘗試如下腳本 ```shell # 保存為xgdb.sh（添加可執行權限） # 用法 xgdb.sh a prog_bin=$1 running_name=$(basename $prog_bin) pid=$(/sbin/pidof $running_name) gdb attach $pid ``` 另一種是先啟動gdb，然后用“attach”命令“附著”在進程上： 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 如果不想繼續調試了，可以用“detach”命令“脫離”進程： (gdb) detach Detaching from program: /data/nan/a, process 10210 (gdb) bt No stack. 詳情參見[gdb手冊](https://sourceware.org/gdb/current/onlinedocs/gdb/Attach.html#index-attach) ## 貢獻者 nanxiao