joinfiles.sh

#!/bin/bash
#
# Join multiple files


print_usage(){
  echo "== joinfiles v0.1alpha =="
  echo "joinfiles joins multiple files in a single one."
  echo ""
  echo "Usage:"
  echo -e "\t./$(basename "$0") OUTPUT-FILE FILE1 FILE2 FILEn"
  echo "or:"
  echo -e "\t./$(basename "$0") OUTPUT-FILE FILE*"
}

# at least 2 arguments
if [[ $# -le 1 ]]; then
  print_usage
  exit 1
fi

function add_file() {
  num_of_lines=$(($(wc -l < "$1") - 1))
  total_lines=$(($total_lines + $num_of_lines))
  echo "Adding $1 ($num_of_lines lines)"
  tail -n +2 $1 >> $OUTPUT_FILE
}

PARAMS=($@)
FILE_LIST=("${PARAMS[@]:1}")

OUTPUT_FILE=${PARAMS[0]}
echo "Creating file: $OUTPUT_FILE"

for idx in "${!FILE_LIST[@]}"; do
  if [[ "$idx" -eq "0" ]]; then
    # insert header based on first file's header
    head -1 ${FILE_LIST[idx]} > $OUTPUT_FILE
  fi
  add_file ${FILE_LIST[idx]}
done

echo "Checking $OUTPUT_FILE..."
num_of_lines=$(($(wc -l < "$OUTPUT_FILE") - 1))
if [[ $num_of_lines == $total_lines ]]; then
  echo "OK! $num_of_lines lines read. $total_lines lines written."
else
  echo "Ooops! Check file: $num_of_lines lines read. $total_lines lines written."
fi

exit 0