小编Neh*_*ani的帖子

我在Fedora中有两个用户:

1. 迩
2. root(非常明显!)

用户Wani的.bashrc的内容是:

# .bashrc
echo "Hello"
# Source global definitions
if [ -f /etc/bashrc ]; then
    . /etc/bashrc
fi

# User specific aliases and functions

登录到root后,我输入以下命令:

[root@Dell Wani]# touch try.txt
[root@Dell Wani]# service sshd start
[root@Dell Wani]# scp try.txt Wani@localhost:~/
Wani@localhost's password: 
Hello
[root@Dell Wani]# 

现在我登录Wani,输入:

[Wani@Dell ~]$ cat try.txt
cat: try.txt: No such file or directory
[Wani@Dell ~]$ 

现在我再次登录root并输入相同的命令-v:

[root@Dell Wani]# scp -v morph.log Wani@localhost:
Executing: program /usr/bin/ssh host localhost, user Wani, command scp -v …

为什么以下抛出异常,虽然它成功了？

>>> t = ([1, 2, 3], 4)
>>> t[0] += [1]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'tuple' object does not support item assignment
>>> t
([1, 2, 3, 1], 4)
>>> 

我正在尝试在Mac OS 10.11.6上的Anaconda3 python 3.6上安装OpenCV 3.2.0,但我找不到办法.我的Anaconda3安装了python 3.5.2,但如果我使用创建一个新的虚拟环境

$ conda create -n myvenv python  
then it downloads and installs python 3.6 on the new myvenv. A simple search  
$ conda search opencv
opencv                       2.4.8                np17py27_2  defaults 

而opencv3没有结果

$ conda search opencv3
NoPackagesFoundError: Package missing in current osx-64 channels: 
  - opencv3

安装menpo opencv3 build会产生以下冲突:

$ conda install -c menpo opencv3
Fetching package metadata ...........
Solving package specifications: .
UnsatisfiableError: The following specifications were found to be in conflict:
  - opencv3 -> python …

我知道我的问题在这里有一个答案:QFile寻求表现.但我对答案并不完全满意.即使在查看generic_file_llseek()ext4 的以下实现之后,我似乎也无法理解如何测量复杂性.

/**
 * generic_file_llseek - generic llseek implementation for regular files
 * @file:       file structure to seek on
 * @offset:     file offset to seek to
 * @origin:     type of seek
 *
 * This is a generic implemenation of ->llseek useable for all normal local
 * filesystems.  It just updates the file offset to the value specified by
 * @offset and @origin under i_mutex.
 */
loff_t generic_file_llseek(struct file *file, loff_t offset, int origin)
{
        loff_t rval; …

检查我的python程序在哪个shell中运行的推荐方法是什么？我知道我可以查询os.environ.get('SHELL')shell 名称，但是我可以使用什么来确定 powershell？

源代码：

#include <cstdio>\n\nstatic const char encodeBase64Table[64 + 1] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";\n\nint main() {\n    // create decoding table\n    unsigned long invalid = 64;\n    unsigned long decodeBase64Table[256] = {};\n    for (unsigned long i = 0; i < 256; i++)\n        decodeBase64Table[i] = invalid;\n    for (unsigned long i = 0; i < 64; i++) {\n        decodeBase64Table[(unsigned char)encodeBase64Table[i]] = i;\n    }\n    printf("decodeBase64Table[65] = %lu\\n", decodeBase64Table[65]);\n\n    return 0;\n}\n

Apple Clang 11.0.3（预期输出，即使使用 -O3）：

/t/s/1673994196 \xe2\x9d\xaf\xe2\x9d\xaf\xe2\x9d\xaf /usr/bin/clang++ --version\nApple clang version 11.0.3 (clang-1103.0.32.62)\nTarget: x86_64-apple-darwin21.6.0\nThread model: posix\nInstalledDir: /Library/Developer/CommandLineTools/usr/bin\n/t/s/1673994196 …

为什么 UDP 在其数据包中有两次“UDP 长度”字段？不是多余的吗？如果需要进行某种错误检查，请提供示例。