I've got the following one-liner with Perl:
perl -MLingua::EN::Sentence=get_sentences -ne 'print "$_\n" for grep { /replace_me/i } @{get_sentences($_)}' "${filePath}"
How can I restructure this so that I'm able to replace the "replace_me" section with any string of text (aka, a variable) that I can pass into the script as an argument?
I understand that you cannot add variables within single quotes, but I'm not sure how to restructure this at the moment with double quotes. Any help would be appreciated.
A "one-liner" is a program that can take input like any other -- what is passed to the program at invocation is in @ARGV array.
Then there are two particular issues to take into account
With -n the code under '' is the body of a loop (over lines from the files that are processed or from STDIN) so you want to extract your input (arguments) in a BEGIN block, before the runtime and so before the loop starts
Arguments that are passed to the script must be removed from @ARGV so that what remains are only filename(s), to be read line by line (under -n, or -p)
Then there are three ways to bring arguments into the program.
Fetch the arguments from @ARGV by hand
perl -wnE'BEGIN { $input = shift }; ... ' "input string" filename(s)
where ... stand for your code, just as it was, but which now can use $input.
Another way is with -s switch which enables a rudimentary mechanism for arguments
perl -s -wnE'...code using $input...' -- -input="input string" filename(s)
where the name given after - (I used input above) is the name of the variable in which input gets stored. The -- are there to mark the beginning of the arguments. All arguments passed to the script must be given before the filename(s).
Finally, instead of passing arguments directly we can set a shell variable as an environment variable, which the script can then see. In bash shell we can do it in the same command-line, right before the command itself
input="input string" perl -wnE'...$ENV{input}...' filenames
Or, set it up beforehand and export it
export input="input string"
perl -wnE'... $ENV{input} ...'
See this post for details on all three ways.
Once this input is used in a regex escape it using quotemeta, /...\Q$input\E.../i, unless it is meant to be a ready regex pattern. Please see the linked documentation.