How to delete a line of the text file from the output of checklist - bash

Question

I have a text file:
$100 Birthday
$500 Laptop
$50 Phone
I created a --checklist from the text file
[ ] $100 Birthday
[*] $500 Laptop
[*] $50 Phone
the output is $100 $50
How can I delete the line of $100 and $50 in the text file, please?
The expected output of text file:
$100 Birthday
Thank you!

Answer 1

with grep and cut
grep -xf <(grep '\[ ]' file2.txt | cut -d\ -f3-) file1.txt
with grep and sed
grep -xf <(sed -rn 's/\[ ]\s+(.*)/\1/p' file2.txt) file1.txt
explanation
use grep to select lines from text file
$ grep Birthday file1.txt
100 Birthday
cut will split line into columns. -f 2 will print only 2nd column but -f 2- will print everything from 2nd column. as delimiter -d whitespace ' ' is used here (some character must escaped with \)
and we can use pipe | as input (instead file)
$ echo one two three | cut -d \ -f 2-
two three
$ grep Birthday file1.txt | cut -d \ -f 2-
Birthday ^
|
(note the two whitespaces) --------+
assuming we have a text file temp.txt
$ cat temp.txt
Birthday
Laptop
Phone
grep can also read list of search patterns from another file as input instead
$ grep -f temp.txt file1.txt
100 Birthday
500 Laptop
50 Phone
or we print the file content with cat and redirect output with <
$ grep -f <(cat temp.txt) file1.txt
100 Birthday
500 Laptop
50 Phone
Now let's generate temp.txt from checklist. You only want grep lines containing [ ] and cut starting from 3rd column (again some characters have special meaning and must therefore escaped \[)
$ grep '\[ ]' file2.txt
[ ] 100 Birthday
$ grep '\[ ]' file2.txt | cut -d\ -f3-
100 Birthday
You don't need temp.txt and can therefore redirect list straight to grep -f what is called process substitution <(...)
$ grep -f <(grep '\[ ]' file2.txt | cut -d\ -f3-) file1.txt
100 Birthday
grep read all lines from temp.txt as PATTERN and some characters have special meaning for regex. ^ stands for begin of line and $ for end of line. To be nitpicky correct search pattern should therefore be '^100 Birthday$' so it won't match "1100 Birthday 2".
You might have noticed that I dropped the $ currency in your input files for reason. You can keep it, but tell grep to take all input literally with -F and(/or?) -x flag which will search for whole line "100 Birthday" (no regex for line start/ending needed)
sed [OPTION] 's/regexp/replacement/command' [file]
sed is more common when it comes to text editing. instead grep | cut we can do it from one single command:
grep '\[ ]' | cut -f3- and sed 's/\[ ] *//'
are basically targeting the same lines and delete [ ] from it.
There are however some extra flags required, because sed is text editor and will stream the whole file by default. to emulate grep's behavior we use
-n option to suppress the input
p command to print only changes
and for regexp
\[ ] (text to replace)
' *' = ' ' (whitespace) + * (star)
meaning: repeated previous character 0 or more times, in particulary all trailing whitespaces
(replacement is empty because we want just delete)
so working similar sed command will look like this
sed -n 's/\[ ] *//p' file2.txt
And that's in my opinion all it takes for a checklist. You have however two redundant files and want match your cloned checklist against original file, so let me show you more complicated things.
Instead of deleting the checkbox let's output captured groups. This pseudo code will explain it better than me. \1 is for first capture group ( ) and so on (kinda internal variables)
$ sed 's/(aaa)b(ccc)dd/\1/'
aaa
$ sed 's/(aaa)b(ccc)dd/\2/'
ccc
$ sed 's/(aaa)b(ccc)dd/\1 \2/'
aaa ccc
$ sed 's/(aaa)b(ccc)dd/lets \1 replace \2 this/'
lets aaa replace ccc this
so in this example sed 's/\[ ] (.*)/\1/' we use for regexp
\[ ] (text to replace)
' ' (trailing whitespace)
and inside the first capture group ( ) the desired "100 Birthday"
.* = . (dot) + * (star)
meaning: repeated previous character 0 or more times (in particulary a dot here)
but the dot . itself is regex for ANY char now (special meaning)
so the capture group is all the rest of line
and for replacement we use (only)
\1 first capture group
$ sed -n 's/\[ ] (.*)/\1/p' file2.txt
100 Birthday
But there is more :)
Instead of matching only ' ' whitespace there exist another regex with special meaning (extended regex)
\s will match whitespace and tab
+ repeated previous character 1 or more times (note the difference to * 0 or more times)
\s+ will match a series of spaces
and to make it work we need one more flag
-r use extended regular expressions
so with this command you can extract all search patterns from your cloned checklist...
$ sed -rn 's/\[ ]\s+(.*)/\1/p' file2.txt
100 Birthday
...and finally let it run against your original file (without the need of temp.txt)
$ grep -xf <(sed -rn 's/\[ ]\s+(.*)/\1/p' file2.txt) file1.txt
100 Birthday