How To Install flex on CentOS 8

flex is A tool for creating scanners (text pattern recognizers)

Introduction

In this tutorial we learn how to install flex on CentOS 8.

What is `flex`

The flex program generates scanners. Scanners are programs which can recognize lexical patterns in text. Flex takes pairs of regular expressions and C code as input and generates a C source file as output. The output file is compiled and linked with a library to produce an executable. The executable searches through its input for occurrences of the regular expressions. When a match is found, it executes the corresponding C code. Flex was designed to work with both Yacc and Bison, and is used by many programs as part of their build process. You should install flex if you are going to use your system for application development.

We can use yum or dnf to install flex on CentOS 8. In this tutorial we discuss both methods but you only need to choose one of method to install flex.

Install flex on CentOS 8 Using dnf

Update yum database with dnf using the following command.

sudo dnf makecache --refresh

The output should look something like this:

CentOS Linux 8 - AppStream                                       43 kB/s | 4.3 kB     00:00    
CentOS Linux 8 - BaseOS                                          65 kB/s | 3.9 kB     00:00    
CentOS Linux 8 - ContinuousRelease                               43 kB/s | 3.0 kB     00:00    
CentOS Linux 8 - Extras                                          23 kB/s | 1.5 kB     00:00    
CentOS Linux 8 - FastTrack                                       40 kB/s | 3.0 kB     00:00    
CentOS Linux 8 - HighAvailability                                36 kB/s | 3.9 kB     00:00    
CentOS Linux 8 - Plus                                            24 kB/s | 1.5 kB     00:00    
CentOS Linux 8 - PowerTools                                      50 kB/s | 4.3 kB     00:00    
Extra Packages for Enterprise Linux Modular 8 - x86_64           13 kB/s | 9.2 kB     00:00    
Extra Packages for Enterprise Linux 8 - x86_64                   24 kB/s | 8.5 kB     00:00    
Metadata cache created.

After updating yum database, We can install flex using dnf by running the following command:

sudo dnf -y install flex

Install flex on CentOS 8 Using yum

Update yum database with yum using the following command.

sudo yum makecache --refresh

The output should look something like this:

CentOS Linux 8 - AppStream                                       43 kB/s | 4.3 kB     00:00    
CentOS Linux 8 - BaseOS                                          65 kB/s | 3.9 kB     00:00    
CentOS Linux 8 - ContinuousRelease                               43 kB/s | 3.0 kB     00:00    
CentOS Linux 8 - Extras                                          23 kB/s | 1.5 kB     00:00    
CentOS Linux 8 - FastTrack                                       40 kB/s | 3.0 kB     00:00    
CentOS Linux 8 - HighAvailability                                36 kB/s | 3.9 kB     00:00    
CentOS Linux 8 - Plus                                            24 kB/s | 1.5 kB     00:00    
CentOS Linux 8 - PowerTools                                      50 kB/s | 4.3 kB     00:00    
Extra Packages for Enterprise Linux Modular 8 - x86_64           13 kB/s | 9.2 kB     00:00    
Extra Packages for Enterprise Linux 8 - x86_64                   24 kB/s | 8.5 kB     00:00    
Metadata cache created.

After updating yum database, We can install flex using yum by running the following command:

sudo yum -y install flex

How To Uninstall flex on CentOS 8

To uninstall only the flex package we can use the following command:

sudo dnf remove flex

flex Package Contents on CentOS 8

/usr/bin/flex
/usr/bin/flex++
/usr/bin/lex
/usr/include/FlexLexer.h
/usr/lib/.build-id
/usr/lib/.build-id/84
/usr/lib/.build-id/84/a8994b9d460ef2b6ced012f0cd441ddb6ceb3c
/usr/share/doc/flex
/usr/share/doc/flex/NEWS
/usr/share/doc/flex/README
/usr/share/info/flex.info-1.gz
/usr/share/info/flex.info-2.gz
/usr/share/info/flex.info.gz
/usr/share/licenses/flex
/usr/share/licenses/flex/COPYING
/usr/share/locale/ca/LC_MESSAGES/flex.mo
/usr/share/locale/da/LC_MESSAGES/flex.mo
/usr/share/locale/de/LC_MESSAGES/flex.mo
/usr/share/locale/en@boldquot/LC_MESSAGES/flex.mo
/usr/share/locale/en@quot/LC_MESSAGES/flex.mo
/usr/share/locale/eo/LC_MESSAGES/flex.mo
/usr/share/locale/es/LC_MESSAGES/flex.mo
/usr/share/locale/fi/LC_MESSAGES/flex.mo
/usr/share/locale/fr/LC_MESSAGES/flex.mo
/usr/share/locale/ga/LC_MESSAGES/flex.mo
/usr/share/locale/hr/LC_MESSAGES/flex.mo
/usr/share/locale/ko/LC_MESSAGES/flex.mo
/usr/share/locale/nl/LC_MESSAGES/flex.mo
/usr/share/locale/pl/LC_MESSAGES/flex.mo
/usr/share/locale/pt_BR/LC_MESSAGES/flex.mo
/usr/share/locale/ro/LC_MESSAGES/flex.mo
/usr/share/locale/ru/LC_MESSAGES/flex.mo
/usr/share/locale/sr/LC_MESSAGES/flex.mo
/usr/share/locale/sv/LC_MESSAGES/flex.mo
/usr/share/locale/tr/LC_MESSAGES/flex.mo
/usr/share/locale/vi/LC_MESSAGES/flex.mo
/usr/share/locale/zh_CN/LC_MESSAGES/flex.mo
/usr/share/locale/zh_TW/LC_MESSAGES/flex.mo
/usr/share/man/man1/flex++.1.gz
/usr/share/man/man1/flex.1.gz
/usr/share/man/man1/lex.1.gz

References

flex website

Summary

In this tutorial we learn how to install flex on CentOS 8 using yum and dnf.