#!/bin/bash
# ideone boilerplate - we can't write files in the home directory;
# so create a temporary directory for our files instead
t=$(mktemp -d -t ideone.XXXXXXXXXXXX) || exit
trap 'rm -rf "$t"' ERR EXIT
cd "$t"
 
cat <<\: >filea.csv
Foo,Bar,Baz,Quux,There is #Corona and #Covid here,False positive?
Foo,Bar,Baz,Quux,There is Corona and #Covid here,This should be matched
Foo,Bar,Baz,Quux,There is #Corona and Covid here,This should be matched
Foo,Bar,Baz,Quux,There is #Corona and #Covid here,False positive?
Foo,Bar,Baz,Quux,"Quoted comma, There is Corona and Covid here",False negative for non-Python/grep -P cases
Corona,Covid,Baz,Quux,There is #Corona and #Covid here,False positive for grep -P case
:
 
 
cat <<\: >prog.py
#!/usr/bin/env python3
 
import csv
import re
import sys
 
reader = csv.reader(sys.stdin)
writer = csv.writer(sys.stdout)
for line in reader:
    if re.search(r'(?<!#)\b(?:Corona|Covid)\b', line[4], re.IGNORECASE):
        writer.writerow(line)
:
 
 
echo '** grep -P **'
grep -Pwi '(?<!#)(Corona|Covid)' filea.csv
 
echo
echo '** grep -E **'
grep -Ei '^([^,]*,){4}(#?[^,#]+)*\b(Corona|Covid)\b' filea.csv
 
echo
echo '** awk **'
awk -F, -v col=5 '{ field = tolower($col); gsub(/#[A-Za-z0-9_]+/, "", field) }
  field ~ /\<(corona|covid)\>/' filea.csv
 
 
echo
echo '** python3 **'
python3 prog.py <filea.csv
 

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