Finding emails from one file in another

I want to find emails from one file listed as such:

[e-mail]
[e-mail]
[e-mail]

in another file listed as so:

[e-mail]:[phone]
[e-mail]:[phone]
[e-mail]:[phone]
[e-mail]:[phone]

and output the lines from the second file that match with the first file also keeping in mind it needs to match the entire email from start to finish so it won’t match [e-mail] accidently.

Desired output:

[e-mail]:[phone]
[e-mail]:[phone]

Thanks!

Answer

With grep, get the newline separated patterns (strings here, -F) from an input file with -f, and match with the other file:

grep -Ff email.txt file.txt 

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With awk, keeping an array with emails as indexes and checking if the first field of each record in the second file is an index:

awk -F: 'NR==FNR{a[$0]=1; next} a[$1]' email.txt file.txt

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Example:

% cat email.txt 
[e-mail]
[e-mail]
[e-mail]

% cat file.txt
[e-mail]:[phone]
[e-mail]:[phone]
[e-mail]:[phone]
[e-mail]:[phone]

% grep -Ff email.txt file.txt 
[e-mail]:[phone]
[e-mail]:[phone]


% cat email.txt                                                  
[e-mail]
[e-mail]
[e-mail]

% cat file.txt
[e-mail]:[phone]
[e-mail]:[phone]
[e-mail]:[phone]
[e-mail]:[phone]

% awk -F: 'NR==FNR{a[$0]=1; next} a[$1]' email.txt file.txt
[e-mail]:[phone]
[e-mail]:[phone]