Duplicate line in csv file

Question

I have a script that removes Contacts from a csv file.

Csv file is like: First Name,Last Name,Phone Number

Example: John,Doe,2109428409

Script asks user to input Last Name and whole line gets erased. If there's a duplicate last name in the csv file how can I ask the user first name of one of the two contact he wants to delete? Here's my code

  #!/bin/bash

  echo "Tell Me The Contact's Last Name you want to delete"
  read LastName
  if grep -q $LastName contacts.csv
  then
  sed -i '/'$LastName'/d' contacts.csv
  else
  echo "The surname you typed doesn't exist or isn't valid"
  fi

if this is just for learning, fine, but if you have real data you want to remove duplicates from, consider sort -u -o datFile datFile . Good luck. — shellter
I am actually trying with the same method not really getting the result I want. And yeah this is just for learning. — user9017239
@CGDominator : grep -c outputs the number of matching lines, so instead of testing whether we have a match, you ask for the number of matches and consider 3 cases: 0 matches, 1 match, more than one match. However, your script has other problems: (1) You are testing for the occurance of $LastName in any place of the CSV file, not only in the column for last names. (2) A malevolent user could enter for what you take as his last name, a regexp pattern which wipes out your whole CSV file. By and large, this is not a problem I personally would solve in Posix shell. — user1934428
You have CSV file, which means your data is somewhat structured. That means you really only want to find the value of $LastName in a specific field, not just anywhere in the line. That makes grep inappropriate for this task. — chepner

Jithin Scaria Jithin Scaria · Accepted Answer · 2017-12-01T07:28:02

We can add something like below, to your script,

#!/bin/bash

  echo "Tell Me The Contact's Last Name you want to delete"
  read LastName
  # --------------------------------------------------------#
  if [ $(grep $LastName contacts.csv | wc -l) -gt 1 ];then  # --> check the count of Last name in file
      echo "enter the first name from below list of contact you want to remove"
      grep $LastName contacts.csv     # --> Display list of entries with same Last Name 
      read firstName                  # --> Read First name Input from user
      sed -i '/'$firstName,$LastName'/d' contacts.csv  # --> delete row with first name and Last Name.
  elif [ $(grep $LastName contacts.csv | wc -l) -eq 1 ];then
  # --------------------------------------------------------#
      sed -i '/'$LastName'/d' contacts.csv
  else
      echo "The surname you typed doesn't exist or isn't valid"
  fi

Duplicate line in csv file

1 Answers