gistfile1.txt

#!/bin/bash

num_threads=<num_threads>
pattern_file="pattern_list.txt"
output_file="output.txt"
directory_path="directory_path"

# Read each pattern from the pattern file
while IFS= read -r pattern; do
  # Run grep in the background for each pattern
  grep -r -n "$pattern" "$directory_path" >> "$output_file" &
  # Limit the number of concurrent background processes
  if [[ $(jobs -p | wc -l) -ge $num_threads ]]; then
    wait -n
  fi
done < "$pattern_file"

# Wait for any remaining background processes to finish
wait