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#] "$d_SysMaint"'Linux/str notes.txt'
# www.BillHowell.ca  11Sep2023 initial 
# view in text editor, using constant-width font (eg courier), tabWidth = 3

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# Table of Contents, generate with :
# $ grep  "^#]"  "$d_SysMaint"'Linux/str notes.txt'  |  sed "s/^#\]/  /" 
#


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# Setup, ToDos,   


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#] ??Feb2024 


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#] ??Feb2024 


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#] 01Feb2024 bash str length, add a chr
see:  str_chrP_rmBetween()  - rm chrs between chr[start, end] = chrP, chrP example '{}'
in "$d_bin"'strings.sh'


+-----+
https://linuxhandbook.com/bash-string-length/
How to Find Length of String in Bash [Quick Tip]
Here are various ways to calculate the length of a string in bash scripts.
Aug 26, 2020 — Abhishek Prakash 

${#my_string}

One of these commands is the expr command. It has several options that are useful for string options. Among them, length gives you the length of a string.
abhishek@handbook:~$ expr length "my string"
9

You'll have to use echo command and then use pipe redirection to parse it with awk:
abhishek@handbook:~$ echo "my string" | awk '{print length}'
9

You can echo the string and pipe it to wc command. The -m option gives the character count.
abhishek@handbook:~$ echo -n "my string" | wc -m
9
Notice the -n option with echo command? That is important because echo automatically adds a new line character \n at the end and it will increase the length of the string by one. With -n option, echo command doesn't add new line character.

search "Linux bash Segmentation fault (core dumped)"

+-----+
https://unix.stackexchange.com/questions/277331/segmentation-fault-core-dumped-to-where-what-is-it-and-why
Segmentation fault (core dumped) - to where? what is it? and why?
Asked 7 years, 9 months ago
Modified 1 year, 7 months ago
Viewed 156k times

>> too advanced for me - I don't want to wander through a core dump, just want to fix my script (famous last words)

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https://www.baeldung.com/linux/segmentation-fault-core-dumped
Segmentation Faults and Fixing the Segmentation fault (core dumped) Error
Last updated: January 11, 2024
Written by: Hiks Gerganov

I temporarily unchecked "Block pop-up windows" in FireFox meanu -> Sttings -> Privacy & Security -> permissions down the window
>> still got message







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#] 01Feb2024 Extracting a Substring in Bash: ${VAR:start_index:length}, or $ cut -c 5-9 <<< '0123Linux9'

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https://www.baeldung.com/linux/bash-substring
Extracting a Substring in Bash
Last updated: May 11, 2023
Written by: Kai Yuan

3.1. Using the cut Command

We can extract from the Nth to the Mth character from the input string using the cut command: cut -c N-M. 
As we discussed in an earlier section, our requirement is to take the substring from index 4 through index 8.
Here, when we talk about the index, it’s in Bash’s context, which means it’s a 0-based index.
Therefore, if we want to solve the problem using the cut command, we need to add one to the beginning and ending index. Thus, the range will become 5-9.

Now let’s see if the cut command can solve the problem:
	$ cut -c 5-9 <<< '0123Linux9'
	Linux
As the output shows, we got the expected substring, “Linux“, so problem solved.
In the example above, we passed the input string to the cut command via a here-string and saved an echo process.


3.3. Using Bash’s Substring Expansion

We’ve seen how cut and awk can easily extract index-based substrings.

Alternatively, Bash is sufficient to solve the problem, since it supports substring expansion via ${VAR:start_index:length}. 

Today, Bash is the default shell for many modern Linux distros. In other words, we can solve the problem without using any external command:

$ STR="0123Linux9"
$ echo ${STR:4:5}
Linux

As we can see in the output above, we solved the problem using pure Bash.

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#] 11Sep2023 search "Linux and how do I get the length of a string?"

+-----+
https://linuxhandbook.com/bash-string-length/
How to Find Length of String in Bash [Quick Tip]
Here are various ways to calculate the length of a string in bash scripts. 
Abhishek Prakash
Sep 1, 2021 • 2 min read

Thankfully, getting length of string in bash is super simple. Let's say you have a string named my_string. Its length can be extracted as:
	${#my_string}



# enddoc