Shell

Shell, also known as Bourne Shell Programming written by Steve Bourne, appeared in the 7th Edition Bell Labs Research of Unix. Its purpose is to automate computing procedures such as a list of commands, pretty much like a cooking recipe to a chef.

Overview of the Guide

For this section of guides, you will learn SHELL as a programming language (yes it is possible) but comes as a price: self-discipline. Otherwise, abusing it might ends up another stage of Javascript horror. There are 2 main variants I'm currently supporting:

1. The POSIX Compliant Bourne Shell (also known as sh)
2. The Bourne-Again Shell (known as BASH)

Why bash? more of the supports across Linux OSes and commonly used in desktop and server.

Shell Usefulness

Folks learn shell script mainly for:

1. fun and easy to use
2. integrate various complexity of programs together easily
3. automation

Of course, once in a while, you'll meet some crazy folks like me who turn it into a day-to-day programming language.

Supported Types

There are various Shell variants in the market. In this guide, we only focus on 2 types:

• POSIX compliant type - the one that works everywhere
• BASH type - the one upgraded for using shell as a programming languages

What to do Next

If you're ready, use the navigation bar to find the guide of the one type you're looking for. I had arranged the topic in a sequential manner for easy references. You can also read through the materials I did for producing this guide!

References

1. http://wiki.bash-hackers.org/scripting/debuggingtips
2. https://www.thegeekstuff.com/2008/09/bash-shell-take-control-of-ps1-ps2-ps3-ps4-and-prompt_command/
3. https://stackoverflow.com/questions/13710806/how-to-replace-placeholder-character-or-word-in-variable-with-value-from-another
4. https://stackoverflow.com/questions/11650840/linux-remove-redundant-paths-from-path-variable
5. https://www.amazon.com/gp/search?index=books&linkCode=qs&keywords=9781118024485
6. https://www.gnu.org/software/bash/manual/html_node/The-Shopt-Builtin.html
7. http://pubs.opengroup.org/onlinepubs/9699919799/utilities/test.html
8. http://mywiki.wooledge.org/BashFAQ/031
9. http://mywiki.wooledge.org/
10. https://serverfault.com/questions/52034/what-is-the-difference-between-double-and-single-square-brackets-in-bash
11. http://mywiki.wooledge.org/BashPitfalls
12. http://mywiki.wooledge.org/BashGuide/TestsAndConditionals
13. https://stackoverflow.com/questions/44688460/bash-script-pattern-matching
14. https://www.tldp.org/LDP/abs/html/subshells.html
15. https://mywiki.wooledge.org/BashProgramming
16. http://wiki.bash-hackers.org/syntax/pe
17. https://www.gnu.org/software/bash/manual/html_node/Bash-POSIX-Mode.html
18. http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_06_02
19. https://stackoverflow.com/questions/6499486/how-to-mark-an-array-in-posix-sh
20. https://stackoverflow.com/questions/34434157/posix-sh-syntax-for-for-loops-sc2039
21. http://tldp.org/LDP/GNU-Linux-Tools-Summary/html/x11655.htm
22. https://stackoverflow.com/questions/35693980/test-for-regex-in-string-with-a-posix-shell
23. https://stackoverflow.com/questions/21115121/how-to-check-pattern-match-by-using-bin-sh-not-by-bin-bash
24. https://unix.stackexchange.com/questions/409065/how-does-curly-brace-expansion-work-in-the-shell
25. http://www.linfo.org/wildcard.html
26. https://unix.stackexchange.com/questions/37313/how-do-i-grep-for-multiple-patterns-with-pattern-having-a-pipe-character
27. https://askubuntu.com/questions/621981/for-loop-syntax-in-shell-script
28. https://stackoverflow.com/questions/34256437/shell-bash-how-to-prompt-a-user-to-select-from-a-dynamically-populated-list
29. https://aty.sdsu.edu/bibliog/latex/debian/bash.html
30. https://stackoverflow.com/questions/40681745/capitalize-each-input-string-in-shell-script
31. https://unix.stackexchange.com/questions/312280/split-string-by-delimiter-and-get-n-th-element
32. https://stackoverflow.com/questions/51052475/how-to-iterate-over-the-characters-of-a-string-in-a-posix-shell-script
33. https://stackoverflow.com/questions/369758/how-to-trim-whitespace-from-a-bash-variable
34. https://www.unix.com/shell-programming-and-scripting/17374-strip-leading-trailing-spaces-only-shell-variable-embedded-spaces.html
35. https://stackoverflow.com/questions/10929453/read-a-file-line-by-line-assigning-the-value-to-a-variable
36. https://pubs.opengroup.org/onlinepubs/009695399/utilities/read.html
37. https://stackoverflow.com/questions/5014823/how-to-profile-a-bash-shell-script-slow-startup
38. https://askubuntu.com/questions/915132/measure-performance-of-a-fast-bash-script
39. https://www.linuxquestions.org/questions/linux-newbie-8/time-difference-calculation-4175459414/
40. https://askubuntu.com/questions/274349/getting-cpu-usage-realtime
41. https://stackoverflow.com/questions/3601515/how-to-check-if-a-variable-is-set-in-bash