conda 進入虛擬環境：
1、conda 命令行安裝
conda install pytorch torchvision cudatoolkit=10.2 -c pytorch
但出現以下錯誤
錯誤原因：
1.問題描述：conda無法創建虛擬環境並且無法安裝其他第三方包，報錯內容如下：
2.錯誤原因：默認鏡像源訪問速度過慢，會導致超時從而導致更新和下載失敗。
3.解決方案一、更換鏡像源爲清華鏡像源，並且刪除默認鏡像源。
解決方案二、不正常國內訪問途徑
其他可能的問題： 方案一和方案二可能會衝突，如果換了源需要換回正常訪問途徑再執行。
需要關閉，再使用方案一。
2、換清華源安裝
不正常國內訪問途徑先關閉，換源後，命令行去掉最後兩個參數
conda install pytorch torchvision cudatoolkit=10.2
但執行之後選了yes,出現新錯誤:
在這裏插入代碼片
# >>>>>>>>>>>>>>>>>>>>>> ERROR REPORT <<<<<<<<<<<<<<<<<<<<<<
Traceback (most recent call last):
File "/opt/anaconda3/lib/python3.7/site-packages/conda/exceptions.py", line 819, in __call__
return func(*args, **kwargs)
File "/opt/anaconda3/lib/python3.7/site-packages/conda/cli/main.py", line 78, in _main
exit_code = do_call(args, p)
File "/opt/anaconda3/lib/python3.7/site-packages/conda/cli/conda_argparse.py", line 77, in do_call
exit_code = getattr(module, func_name)(args, parser)
File "/opt/anaconda3/lib/python3.7/site-packages/conda/cli/main_install.py", line 11, in execute
install(args, parser, 'install')
File "/opt/anaconda3/lib/python3.7/site-packages/conda/cli/install.py", line 253, in install
handle_txn(unlink_link_transaction, prefix, args, newenv)
File "/opt/anaconda3/lib/python3.7/site-packages/conda/cli/install.py", line 282, in handle_txn
unlink_link_transaction.execute()
File "/opt/anaconda3/lib/python3.7/site-packages/conda/core/link.py", line 223, in execute
self.verify()
File "/opt/anaconda3/lib/python3.7/site-packages/conda/common/io.py", line 46, in decorated
return f(*args, **kwds)
File "/opt/anaconda3/lib/python3.7/site-packages/conda/core/link.py", line 200, in verify
self.prepare()
File "/opt/anaconda3/lib/python3.7/site-packages/conda/core/link.py", line 192, in prepare
stp.remove_specs, stp.update_specs)
File "/opt/anaconda3/lib/python3.7/site-packages/conda/core/link.py", line 282, in _prepare
mkdir_p(transaction_context['temp_dir'])
File "/opt/anaconda3/lib/python3.7/site-packages/conda/gateways/disk/__init__.py", line 60, in mkdir_p
makedirs(path)
File "/opt/anaconda3/lib/python3.7/os.py", line 221, in makedirs
mkdir(name, mode)
PermissionError: [Errno 13] Permission denied: '/opt/anaconda3/.condatmp'
`$ /opt/anaconda3/bin/conda install pytorch torchvision cudatoolkit=10.2`
environment variables:
CIO_TEST=<not set>
CONDA_DEFAULT_ENV=base
CONDA_EXE=/opt/anaconda3/bin/conda
CONDA_PREFIX=/opt/anaconda3
CONDA_PROMPT_MODIFIER=
CONDA_PYTHON_EXE=/opt/anaconda3/bin/python
CONDA_ROOT=/opt/anaconda3
CONDA_SHLVL=1
DEFAULTS_PATH=/usr/share/gconf/ubuntu.default.path
LD_LIBRARY_PATH=/usr/local/cuda-10.0/lib64
MANDATORY_PATH=/usr/share/gconf/ubuntu.mandatory.path
PATH=/usr/local/cuda-10.2/bin:/opt/anaconda3/bin:/home/yuuzh/bin:/home/yuuz
h/.local/bin:/usr/local/cuda/bin:/usr/local/sbin:/usr/local/bin:/usr/s
bin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin}
REQUESTS_CA_BUNDLE=<not set>
SSL_CERT_FILE=<not set>
XDG_SEAT_PATH=/org/freedesktop/DisplayManager/Seat0
XDG_SESSION_PATH=/org/freedesktop/DisplayManager/Session0
active environment : base
active env location : /opt/anaconda3
shell level : 1
user config file : /home/yuuzh/.condarc
populated config files : /home/yuuzh/.condarc
conda version : 4.5.11
conda-build version : 3.15.1
python version : 3.7.0.final.0
base environment : /opt/anaconda3 (read only)
channel URLs : https://mirrors.tuna.tsinghua.edu.cn/anaconda/pkgs/main/linux-64
https://mirrors.tuna.tsinghua.edu.cn/anaconda/pkgs/main/noarch
https://mirrors.tuna.tsinghua.edu.cn/anaconda/pkgs/free/linux-64
https://mirrors.tuna.tsinghua.edu.cn/anaconda/pkgs/free/noarch
https://mirrors.tuna.tsinghua.edu.cn/anaconda/cloud/conda-forge/linux-64
https://mirrors.tuna.tsinghua.edu.cn/anaconda/cloud/conda-forge/noarch
https://mirrors.tuna.tsinghua.edu.cn/anaconda/cloud/msys2/linux-64
https://mirrors.tuna.tsinghua.edu.cn/anaconda/cloud/msys2/noarch
package cache : /opt/anaconda3/pkgs
/home/yuuzh/.conda/pkgs
envs directories : /home/yuuzh/.conda/envs
/opt/anaconda3/envs
platform : linux-64
user-agent : conda/4.5.11 requests/2.19.1 CPython/3.7.0 Linux/4.15.0-106-generic ubuntu/16.04 glibc/2.23
UID:GID : 1000:1000
netrc file : None
offline mode : False
An unexpected error has occurred. Conda has prepared the above report.
If submitted, this report will be used by core maintainers to improve
future releases of conda.
Would you like conda to send this report to the core maintainers?
[y/N]: y
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by running
$ conda config --set report_errors true
原因：
原因是軟件沒有權限進行創建設置的，所以這裏推薦的手動創建設置，以下是設置方法
解決辦法：
conda常用的命令。
1）conda list 查看安裝了哪些包。
2）conda env list 或 conda info -e 查看當前存在哪些虛擬環境
3）conda update conda 檢查更新當前conda
1、先創建虛擬環境
conda create -n your_env_name python=X.X（2.7、3.6等)
2、創建成功，後激活環境
# To activate this environment, use
#
# $ conda activate pytorch-env
#
# To deactivate an active environment, use
#
# $ conda deactivate
對虛擬環境中安裝額外的包。
使用命令conda install -n your_env_name [package]即可安裝package到your_env_name中
關閉虛擬環境(即從當前環境退出返回使用PATH環境中的默認python版本)。
使用如下命令即可。
Linux: source deactivate
Windows: deactivate
刪除虛擬環境。
使用命令conda remove -n your_env_name(虛擬環境名稱) --all， 即可刪除。
刪除環境中的某個包。
使用命令conda remove --name your_env_name package_name 即可。
激活虛擬環境後再執行上述報錯命令：
conda install pytorch torchvision cudatoolkit=10.2
最後執行結果如下
最後，驗證 torch 是否安裝成功：
驗證pytorch是否安裝成功（linux）
要顯示顯卡信息，在終端輸入：
sudo lshw -c video
要顯示CUDA信息，在終端輸入：
nvcc -V
查看Phthon版本，在終端輸入：
python --version
驗證pytorch是否安裝成功，在終端進入python環境
此時進入python環境。
然後，繼續輸入
import torch
import torchvision
不報錯就表明安裝成功。
記住，一定要進入 conda 的虛擬環境哦。