仮想環境内のCentOS環境構築で凡ミスをしたため記録。
Python(Django)-MySQL環境を構築するにあたり以下のエラーに遭遇。


$ pip install mysqlclient
Collecting mysqlclient
  Using cached https://files.pythonhosted.org/packages/4d/38/c5f8bac9c50f3042c8f05615f84206f77f03db79781db841898fde1bb284/mysqlclient-1.4.4.tar.gz
Installing collected packages: mysqlclient
  Running setup.py install for mysqlclient ... error
    ERROR: Command errored out with exit status 1:
     command: /usr/local/bin/python3.7 -u -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'/tmp/pip-install-zqpistk9/mysqlclient/setup.py'"'"'; __file__='"'"'/tmp/pip-install-zqpistk9/mysqlclient/setup.py'"'"';f=getattr(tokenize, '"'"'open'"'"', open)(__file__);code=f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))' install --record /tmp/pip-record-qwlt2ozx/install-record.txt --single-version-externally-managed --compile
         cwd: /tmp/pip-install-zqpistk9/mysqlclient/
    Complete output (32 lines):
    /usr/local/lib/python3.7/distutils/dist.py:274: UserWarning: Unknown distribution option: 'long_description_content_type'
      warnings.warn(msg)
    running install
    running build
    running build_py
    creating build
    creating build/lib.linux-x86_64-3.7
    creating build/lib.linux-x86_64-3.7/MySQLdb
    copying MySQLdb/__init__.py -> build/lib.linux-x86_64-3.7/MySQLdb
    copying MySQLdb/_exceptions.py -> build/lib.linux-x86_64-3.7/MySQLdb
    copying MySQLdb/compat.py -> build/lib.linux-x86_64-3.7/MySQLdb
    copying MySQLdb/connections.py -> build/lib.linux-x86_64-3.7/MySQLdb
    copying MySQLdb/converters.py -> build/lib.linux-x86_64-3.7/MySQLdb
    copying MySQLdb/cursors.py -> build/lib.linux-x86_64-3.7/MySQLdb
    copying MySQLdb/release.py -> build/lib.linux-x86_64-3.7/MySQLdb
    copying MySQLdb/times.py -> build/lib.linux-x86_64-3.7/MySQLdb
    creating build/lib.linux-x86_64-3.7/MySQLdb/constants
    copying MySQLdb/constants/__init__.py -> build/lib.linux-x86_64-3.7/MySQLdb/constants
    copying MySQLdb/constants/CLIENT.py -> build/lib.linux-x86_64-3.7/MySQLdb/constants
    copying MySQLdb/constants/CR.py -> build/lib.linux-x86_64-3.7/MySQLdb/constants
    copying MySQLdb/constants/ER.py -> build/lib.linux-x86_64-3.7/MySQLdb/constants
    copying MySQLdb/constants/FIELD_TYPE.py -> build/lib.linux-x86_64-3.7/MySQLdb/constants
    copying MySQLdb/constants/FLAG.py -> build/lib.linux-x86_64-3.7/MySQLdb/constants
    running build_ext
    building 'MySQLdb._mysql' extension
    creating build/temp.linux-x86_64-3.7
    creating build/temp.linux-x86_64-3.7/MySQLdb
    gcc -pthread -Wno-unused-result -Wsign-compare -DNDEBUG -g -fwrapv -O3 -Wall -fPIC -Dversion_info=(1,4,4,'final',0) -D__version__=1.4.4 -I/usr/include/mysql -I/usr/local/include/python3.7m -c MySQLdb/_mysql.c -o build/temp.linux-x86_64-3.7/MySQLdb/_mysql.o -m64
    gcc -pthread -shared build/temp.linux-x86_64-3.7/MySQLdb/_mysql.o -L/usr/lib64/mysql -lmysqlclient -lpthread -lm -lrt -ldl -o build/lib.linux-x86_64-3.7/MySQLdb/_mysql.cpython-37m-x86_64-linux-gnu.so
    running install_lib
    creating /usr/local/lib/python3.7/site-packages/MySQLdb
    error: could not create '/usr/local/lib/python3.7/site-packages/MySQLdb': Permission denied
    ----------------------------------------
ERROR: Command errored out with exit status 1: /usr/local/bin/python3.7 -u -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'/tmp/pip-install-zqpistk9/mysqlclient/setup.py'"'"'; __file__='"'"'/tmp/pip-install-zqpistk9/mysqlclient/setup.py'"'"';f=getattr(tokenize, '"'"'open'"'"', open)(__file__);code=f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))' install --record /tmp/pip-record-qwlt2ozx/install-record.txt --single-version-externally-managed --compile Check the logs for full command output.

エラーメッセージが多くてどこから見ればいいかわからなくなったが、Permission deniedがカギだった。
原因は、pipを管理者権限なしで実行していたためだった。

$ sudo pip install mysqlclient

で解決。
基本的すぎて恥ずかしい...けどエラーメッセージでググってたどり着く人のために公開。