[SOLVED] Wrap quotes around string in a bash script

taylorkh · 12-22-2017, 12:48 PM

This should not be this hard. Perhaps if I stand on my head

I am sorting out some duplicates in my movie collection. I can search my inventory thus

Code:

[ken@vmCentOS7Mate Desktop]$ grep -i 'pink horse' myflicks.txt 
Ride The Pink Horse                               1947 noir avi

To make for a little less typing I wish to create a script which will accept the search string and then do the search. Should not be difficult.

Code:

#!/bin/bash
read check4
clear
grep -i $check4 myflicks.txt
exit

This will of course work on single words. If I want to search on a multiple word string it must be wrapped in quotes. I have attempted to concatenate quotes to the string thus

Code:

check4="'"$check4"'"

and several other permutations such as wrapping quotes in quotes, escaping the single quotes etc. No luck. I am obviously overlooking something. Any suggestions?

TIA,

Ken

MadeInGermany · 12-22-2017, 12:58 PM

As always in scripts, variables in command arguments should be in "quotes"!

Code:

grep -i "$check4" myflicks.txt

taylorkh · 12-22-2017, 01:16 PM

Thanks MadeInGermany,

That did the trick although I am not quite sure why. I guess it causing grep to treat whatever is in the variable as a single "chunk." If I echo $check4 and echo "check4" I see the same thing. The script must interpret it differently. Bottom line, I am good to go.

Many thanks,

Ken

MadeInGermany · 12-22-2017, 04:46 PM

It is the shell that first does variable expansion then word splitting then globbing (replacing wildcards with matching filenames).
The result is passed to grep as arguments.
The "quotes" let the shell only expand variables.
The quotes are removed also; grep sees the string without the quotes.

taylorkh · 12-23-2017, 03:41 PM

Amazing!

I need to teach my mind to think like a shell (or perhaps find a shell which thinks like my mind). Or perhaps not

Thanks again,

Ken

rnturn · 12-24-2017, 10:37 AM

Quote:

Originally Posted by MadeInGermany

As always in scripts, variables in command arguments should be in "quotes"!

Code:

grep -i "$check4" myflicks.txt

Just make sure they're double quotes---single quotes have a different "gotcha" effect.