No manual entry for ls See 'man 7 undocumented' for help when manual pages are not available.

如果在执行`man`命令时提示`No manual entry`，并且提示查看`man 7 undocumented`，那么可能是因为您的系统中没有安装对应的`man`文档。

您可以尝试使用以下命令来重新安装`man`文档：

sudo apt-get install --reinstall man-db

如果您的系统中已经安装了`man-db`，可以尝试更新`man`文档缓存：

sudo mandb

如果在执行`mandb`命令时提示权限不足，可以尝试使用以下命令：

sudo mandb --user-db

如果您的系统中依然无法找到某个命令的`man`文档，可以尝试在互联网上搜索相关的文档或者手册。

另外，如果您使用的是非英语的Linux系统，可能需要安装对应的语言包才能查看相应的`man`文档。可以尝试安装`manpages-<language>`语言包，例如`manpages-zh`中文语言包。

相关问题

Error #15: Initializing libiomp5md.dll, but found libiomp5md.dll already initialized. OMP: Hint This means that multiple copies of the OpenMP runtime have been linked into the program. That is dangerous, since it can degrade performance or cause incorrect results. The best thing to do is to ensure that only a single OpenMP runtime is linked into the process, e.g. by avoiding static linking of the OpenMP runtime in any library. As an unsafe, unsupported, undocumented workaround you can set the environment variable KMP_DUPLICATE_LIB_OK=TRUE to allow the program to continue to execute, but that may cause crashes or silently produce incorrect results. For more information, please see http://www.intel.com/software/products/support/. libpng warning: iCCP: cHRM chunk does not match sRGB

这个错误信息表明程序中存在多个 OpenMP 运行库的副本，这可能会影响性能或导致错误的结果。最好的解决方法是确保只有一个 OpenMP 运行库被链接到进程中，例如避免在任何库中静态链接 OpenMP 运行库。如果使用不安全、不支持、不文档化的方法，可以设置环境变量 KMP_DUPLICATE_LIB_OK=TRUE 允许程序继续执行，但这可能会导致崩溃或产生错误的结果。了解更多信息，请参见 http://www.intel.com/software/products/support/. 至于 libpng warning: iCCP: cHRM chunk does not match sRGB，它是有关 PNG 图像的警告信息，表明图像中的颜色空间信息与标准 sRGB 不匹配。

gdb undocumented errno 2

`errno 2` corresponds to the error `No such file or directory`.

In GDB, the `errno` command can be used to print the error message associated with the most recent system call error. However, `errno` is not a documented command in GDB and may not be available in all versions or configurations of GDB.

To use `errno` in GDB, you can follow these steps:

1. Set a breakpoint in your program where you expect the error to occur.
2. Run the program until the breakpoint is hit.
3. Use the `errno` command to print the error message associated with the most recent system call error.
4. Continue debugging the program as needed.

Here's an example:

(gdb) break main
(gdb) run
...
Breakpoint 1, main () at main.c:10
10      int fd = open("nonexistent_file.txt", O_RDONLY);
(gdb) errno
$1 = 2
(gdb) continue
Continuing.

Program received signal SIGSEGV, Segmentation fault.
0x00005555555546f3 in main () at main.c:16
16      return 0;

In this example, we set a breakpoint at the beginning of `main`, and then ran the program. When the breakpoint was hit, we used the `open` system call to attempt to open a nonexistent file, resulting in `errno` being set to 2. We then used the `errno` command to print the error message, and continued running the program until it segfaulted.