我正在一个在powerPC设备上运行linux内核3.14的嵌入式系统上工作。 我需要运行一个C ++应用程序，该应用程序应启动系统命令并检索结果。 我尝试了 popen ，但是挂起了。看下面的代码：
#define PATH_MAX_MIO 255
...
FILE *fp;
char path[PATH_MAX_MIO];
fp = popen("ll", "r"); // It hangs here. "ll" is the linux command to view files inside a directory
if (fp == NULL){ return; }
while (fgets(path, PATH_MAX_MIO, fp) != NULL)
std::cout<< path;
pclose(fp);
使用调试器，我可以运行到popen调用为止，直到挂起为止，如果启动命令 top ，我可以看到该进程几乎占用了所有CPU（在90％和99.9％之间变化）。
我不知道为什么会这样。 有什么建议吗？ 谢谢。
.：编辑：。
这是strace -f命令的输出
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5348] <... select resumed> ) = 15 (in [14], left {0, 0})
[pid 5348] select(15, [], NULL, NULL, {0, 0} <unfinished ...>
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5348] <... select resumed> ) = -1 EINTR (Interrupted system call)
[pid 5348] --- SIGPROF {si_signo=SIGPROF, si_code=SI_KERNEL, si_value={int=14594, ptr=0x3902}} ---
[pid 5348] sigreturn() (mask []) = -1 EINTR (Interrupted system call)
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, <unfinished ...>
[pid 5347] --- SIGPROF {si_signo=SIGPROF, si_code=SI_KERNEL, si_value={int=14594, ptr=0x3902}} ---
[pid 5347] <... rt_sigprocmask resumed> [], 8) = 27
[pid 5347] syscall_671098914(0, 0x1, 0xba4bdeda, 0xcbcb28a, 0xb6f76f8c, 0xb6f76f20) = 0
[pid 5348] select(15, [14], NULL, NULL, {0, 0}) = 0 (Timeout)
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, <unfinished ...>
[pid 5348] select(15, [14], NULL, NULL, {0, 0}) = 0 (Timeout)
[pid 5347] <... rt_sigprocmask resumed> [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, <unfinished ...>
[pid 5347] --- SIGPROF {si_signo=SIGPROF, si_code=SI_KERNEL, si_value={int=14594, ptr=0x3902}} ---
[pid 5347] <... rt_sigprocmask resumed> [], 8) = 27
[pid 5347] syscall_268774496(0, 0x10052a5c, 0x28002824, 0xb7a2f008, 0x1, 0xb7a379c0) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5348] select(15, [14], NULL, NULL, {0, 0}) = 0 (Timeout)
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, <unfinished ...>
[pid 5348] select(15, [14], NULL, NULL, {0, 0}) = 0 (Timeout)
[pid 5347] <... rt_sigprocmask resumed> [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, <unfinished ...>
[pid 5347] --- SIGPROF {si_signo=SIGPROF, si_code=SI_KERNEL, si_value={int=14594, ptr=0x3902}} ---
[pid 5347] <... rt_sigprocmask resumed> [], 8) = 27
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
[pid 5347] rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
Ted Lyngmo建议启动仅显示exec *操作的跟踪，结果就是这样：
strace -f ../runtime/Run6 2>&1 | grep -E 'exec[a-z]+\('
execve("../runtime/Run6", ["../runtime/Run6"], [/* 13 vars */]) = 0
[pid 1068] execve("/bin/sh", ["sh", "-c", "cat /proc/version"], [/* 13 vars */]) = 0
[pid 1069] execve("/bin/cat", ["cat", "/proc/version"], [/* 13 vars */]) = 0
然后它再次挂起