Solve the problem that openssl/opensslv. h cannot be found in centos.

Solve the problem that openssl/opensslv. h cannot be found in centos.

Introduction: scrapy is the most famous crawler framework in Python. When installing scrapy, scrapy encountered a problem where a file of openssl could not be found, analyzed, and recorded it.

1. scrapy and Installation Process

Scrapy is a famous crawler framework in Python. I installed it on Centos 7 and found the following problems:

> Pip install scrapy

Due to the large amount of information during the installation process, only the key parts are listed here:

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1. Runningegg_info
2. Writingrequirementstosrc/cryptography. egg-info/requires.txt
3. Writingsrc/cryptography. egg-info/PKG-INFO
4. Writingtop-levelnamestosrc/cryptography. egg-info/top_level.txt
5. Writingdependency_linkstosrc/cryptography. egg-info/dependency_links.txt
6. Writingentrypointstosrc/cryptography. egg-info/entry_points.txt
7. Readingmanifestfile 'src/cryptography. egg-info/SOURCES.txt'
8. Readingmanifesttemplate 'manifest. in'
9. Nopreviusly-includeddirectoriesfoundmatching 'docs/_ build'
10. Warning: nopreviusly-includedfilesmatching '* 'foundunderdirectory 'vectors'
11. Writingmanifestfile 'src/cryptography. egg-info/SOURCES.txt'
12. Runningbuild_ext
13. Generatingcffimodule 'build/temp. linux-x86_64-2.7/_ padding. c'
14. Creatingbuild/temp. linux-x86_64-2.7
15. Generatingcffimodule 'build/temp. linux-x86_64-2.7/_ constant_time.c'
16. Generatingcffimodule 'build/temp. linux-x86_64-2.7/_ openssl. c'
17. Building '_ openssl' extension
18. Creatingbuild/temp. linux-x86_64-2.7/build
19. Creatingbuild/temp. linux-x86_64-2.7/build/temp. linux-x86_64-2.7
20. Gcc-pthread-fno-strict-aliasing-O2-g-pipe-Wall-Wp,-D_FORTIFY_SOURCE = 2-fexceptions-fstack-protector-strong -- param = ssp-buffer-size = 4-grecord-gcc-switches-m64-mtune = generic-D_GNU_SOURCE-fPIC-fwrapv-DNDEBUG-O2-g-pipe-Wall-Wp, -D_FORTIFY_SOURCE = 2-fexceptions-fstack-protector-strong -- param = ssp-buffer-size = 4-grecord-gcc-switches-m64-mtune = generic-D_GNU_SOURCE-fPIC-fwrapv-fPIC-I/usr/include/python2.7-cbuild/temp. linux-x86_64-2.7/_ openssl. c-obuild/temp. linux-x86_64-2.7/build/temp. linux-x86_64-2.7/_ openssl. o
21. Build/temp. linux-x86_64-2.7/_ openssl. c: 434: 30: fatalerror: openssl/opensslv. h: Nosuchfileordirectory
22. # Include <openssl/opensslv. h>
23. ^
24. Compilationterminated.
25. Error: command 'gcc 'failedwithexitstatus1
27. ----------------------------------------
28. Command "/usr/bin/python2-u-c" importsetuptools, tokenize ;__ file __= '/tmp/pip-build-hRMlG0/cryptography/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-ReCoWo-record/install-record.txt -- single-version-externally-managed -- compile" failedwitherrorcode1in/tmp/pip-build-hRMlG0/cryptography/
29. [Root @ AY131203102210033c39Z ~] # Yuminstallopensslbuild/temp. linux-x86_64-2.7/_ openssl. c: 434: 30: fatalerror: openssl/opensslv. h: Nosuchfileordirectory
30. ^ C
32. Exitingonusercancel.

The openssl. c file fails to be installed, and the corresponding file does not appear to be found.

2. Problem Analysis

Check whether openssl is installed:

> Yum info openssl

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1. Loadedplugins: fastestmirror
2. Loadingtransferspeedsfromcachedhostfile
3. * Base: mirrors.aliyun.com
4. * Epel: mirrors.aliyun.com
5. * Extras: mirrors.aliyun.com
6. * Updates: mirrors.aliyun.com
7. InstalledPackages
8. Name: openssl
9. Arch: x86_64
10. Epoch: 1
11. Version: 1.0.1e
12. Release: 60. el7_3.1
13. Size: 1.5 M
14. Repo: installed
15. Summary: UtilitiesfromthegeneralpurposecryptographylibrarywithTLSimplementation
16. URL: http://www.openssl.org/
17. License: OpenSSL
18. Description: TheOpenSSLtoolkitprovidessupportforsecurecommunicationsbetween
19. : Machines. OpenSSLincludesacertificatemanagementtoolandshared
20. : Librarieswhichprovidevariouscryptographicalgorithmsand
21. : Protocols.

Based on the information, we can know that openssl is an installed file. Why is it still missing the openssl. c file?

After some thought, we suddenly found a basic rule that openssl has installed a binary executable program, and here the installation of scrapy requires the openssl source file program, such as openssl. h. Therefore, we need to install the openssh. h development version, which contains the relevant installation source code file.

3. Problem Solving

After confirming the problem, install the openssl-devel installation package:

> Yum install openssl-devel

After the installation is complete, reinstall scrapy to successfully install scrapy.

4. Summary

By extension, there are similar problems in Linux systems. When installing a specific installation package, it depends on some third-party development kits, and some files cannot be found, generally, the development version of the dependent package needs to be installed. This rule should be generic.