1

I'm coding a shell script on my Debian box and there's a line on the script that needs to delete some emails from a textfile that is full of emails, like this:

sed -i '/email01@hotmail.com\|email02@gmail.com\|email03@yahoo.com/d' /myfolder/my_email_list.txt

This command works but as this list is getting kinda big, I was thinking if there is a way for me to store all the emails that I want sed to delete on a list (text file), because when I need a new email to be added, I would just edit the list instead of editing the script and including it in the expression.

Is something like this able to be done?

0

There may well be a way of doing this natively in sed but here are some other options:

  1. grep

    grep -vFf badmails.txt my_email_list.txt > tempfile && 
      mv tempfile my_email_list.txt
    

    Here, you are giving grep a list of patterns (-f) to search for, telling it to treat them as simple strings (-F) and asking for those lines that do not (-v) match any of them. Finally, you redirect the output to a temporary file and then rename the file to overwrite the original.

  2. Perl

    perl -i -e 'open($f,"badmails.txt"); map{$k{$_}++}<$f>; 
                while(<>){print unless defined($k{$_})}' my_email_list.txt 
    

    This opens badmails.txt, saves each line as the key to a hash, then runs through each line of my_email_list.txt (while(<>){}) and prints it unless the same line (email) was present in badmails.txt, that is unless the corresponding value is defined in the hash (print unless defined($k{$_}))

  3. sed and shell:

    while read badmail; do 
      sed -i sed -i "/$badmail/d" my_email_list.txt ;
    done < badmails.txt 
    

    or, use the shell to build the list of mails you want to delete, e.g. me@mine.com\|you@yours.net and pass that to sed:

    bad=$(while read b; do printf "%s\|" "$b"; done < badmails.txt|
          sed 's/\\|$//')
    sed -i "/$bad/d" my_email_list.txt 
    

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