<div>
Fantastic! <br />
<br />
&nbsp;Can you please explain the 3 lines of code below (or tell me which feature to look for) ?<br />
<br />
&nbsp; x=${input:0:$offset}<br />
<br />
&nbsp; &nbsp;x=${x##*}<br />
<br />
&nbsp; echo ${x%%[^0-9]*}
</div>


Fantastic!

 Can you please explain the 3 lines of code below (or tell me which feature to look for) ?

  x=${input:0:$offset}

   x=${x##*}

  echo ${x%%[^0-9]*}

<div>
x=${x##*} <br />
should be<br />
x=${x##*<br />
}<br />
To remove everything up to the last newline in the first $offset characters of $input
</div>


x=${x##*}
should be
x=${x##*
}
To remove everything up to the last newline in the first $offset characters of $input

<div>
<div class="content wysiwyg-content">
The problem I face is easier to explain with an example: <br />
<br />
&nbsp;if given the offset position of letter &quot;h&quot; &nbsp;that is 6, return number 105<br />
&nbsp;if given the offset position of letter &quot;s&quot; &nbsp;that is 57, return number 107<br />
<br />
Here is the input text:<br />
__________________________<wbr />_<br />
105 &nbsp;hello world<br />
<br />
106 &nbsp;today is friday<br />
107 &nbsp;tomorrow is saturday<br />
__________________________<wbr />_<br />
<br />
I am using bash.<br />
<br />
I found that &nbsp;using &quot;expr substr&quot; I can locate the character at the given offset, but don't know how to proceed from there using grep. &nbsp;I am happy with using other tools (sed - my preference- or awk ). If it has to be done with perl &nbsp;I am happy to go that way to but I do not have experience with that language.<br />
<br />
The regular expression would be &quot;^[0-9]* &quot;&nbsp; that is a number followed by a space<br />
<br />
Many thanks in advance for your help
</div>
</div>


The problem I face is easier to explain with an example: 

 if given the offset position of letter "h"  that is 6, return number 105
 if given the offset position of letter "s"  that is 57, return number 107

Here is the input text:
___________________________
105  hello world

106  today is friday
107  tomorrow is saturday
___________________________

I am using bash.

I found that  using "expr substr" I can locate the character at the given offset, but don't know how to proceed from there using grep.  I am happy with using other tools (sed - my preference- or awk ). If it has to be done with perl  I am happy to go that way to but I do not have experience with that language.

The regular expression would be "^[0-9]* "  that is a number followed by a space

Many thanks in advance for your help

Find a regular expression on a line given the character offset of that line

A regular expression ("regex") is a sequence of characters that define a search pattern, mainly for use in pattern matching with strings, or string matching, i.e. "find and replace"-like operations. Regular expression processors are found in several search engines, search and replace dialogs of several word processors and text editors, and in the command lines of text processing utilities, such as sed and AWK. Many programming languages provide regular expression capabilities, some built-in, for example Perl, JavaScript, Ruby, AWK, and Tcl, and others via a standard library, for example .NET languages, Java, Python and C++ (since C++11). Most other languages offer regular expressions via a library.

Regular Expressions

The term 'shell' refers to a general class of text-based command interpreters most often associated with the UNIX and Linux operating systems. Popular shells include Bourne, Debian Almquist (dash), Korn (ksh), Bourne Again (bash) and the C shell family (csh). Some view the DOS 'cmd' prompt as a minimal shell of sorts. It is also possible to install Cygwin on Windows and emulate a full Unix environment with complete shell capabilities. Terminal emulators, such as xterm, GNOME Terminal and OS X Terminal, can be used to access shell.