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Mastering FreeSWITCH

You're reading from  Mastering FreeSWITCH

Product type Book
Published in Jul 2016
Publisher Packt
ISBN-13 9781784398880
Pages 300 pages
Edition 1st Edition
Languages
Concepts
Authors (8):
Russell Treleaven Russell Treleaven
Profile icon Russell Treleaven
Seven Du Seven Du
Profile icon Seven Du
Darren Schreiber Darren Schreiber
Profile icon Darren Schreiber
Ken Rice Ken Rice
Profile icon Ken Rice
Mike Jerris Mike Jerris
Profile icon Mike Jerris
Kalyani Kulkarni Kalyani Kulkarni
Profile icon Kalyani Kulkarni
Florent Krieg Florent Krieg
Profile icon Florent Krieg
Charles Bujold Charles Bujold
Profile icon Charles Bujold
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Toc

Table of Contents (21) Chapters close

Mastering FreeSWITCH
Credits
About the Authors
About the Reviewers
Contributors
www.PacktPub.com
Preface
1. Typical Voice Uses for FreeSWITCH 2. Deploying FreeSWITCH 3. ITSP and Voice Codecs Optimization 4. VoIP Security 5. Audio File and Streaming Formats, Music on Hold, Recording Calls 6. PSTN and TDM 7. WebRTC and Mod_Verto 8. Audio and Video Conferencing 9. Faxing and T38 10. Advanced IVR with Lua 11. Write Your FreeSWITCH Module in C 12. Tracing and Debugging VoIP 13. Homer, Monitoring and Troubleshooting Your Communication Platform Index

Utility functions


We've used a lot of self-written functions. It's time to have a look at them. Let's open the top half of the utils.lua file, in the preceding screenshot.

The first three functions serve mainly to build the fourth function, stamp(), that we use throughout our scripts to do structured logging.

shell() is an example of a typical Lua interaction with an operating system. It executes a command, and returns the output as a string. We use it in stamp() to obtain the result of the command date.

trim() uses Lua native string manipulation, and is equivalent to the chomp() command in Perl, and many similar others in different languages: it deletes the trailing newline in a string, if it exists, and returns the string without the newline.

whichline() comes from the debug package. It returns the current line number in the script, for example, like __line__ in C.

stamp() is our logging workhorse; it takes the string we want to log (our log message), a string (returned by whichline()) representing...

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