bash.sh

#!/bin/bash

directory="/path/to/directory"  # Specify the directory path
output_file="/path/to/output/file.txt"  # Specify the output file path

# Get the current date in the desired format
current_date=$(date +%y%m%d)

# Clear the output file if it exists
> "$output_file"

# Loop through files in the directory in alphabetical order
while IFS= read -r -d $'\0' file_path; do
    # Skip directories
    if [ -d "$file_path" ]; then
        continue
    fi
    
    # Skip empty files or files with less than 3 lines
    if [ $(wc -l < "$file_path") -lt 3 ]; then
        continue
    fi
    
    # Extract lines excluding the first and last lines
    sed '1d;$d' "$file_path" >> "$output_file"
done < <(find "$directory" -type f -print0 | sort -z)

# Add the date at the top of the output file
sed -i "1i $current_date" "$output_file"

# Count the number of lines concatenated (excluding the date line)
line_count=$(( $(wc -l < "$output_file") - 1 ))

# Add the line count at the bottom of the output file
echo "900$line_count" >> "$output_file"

# Print a message when the concatenation is complete
echo "Concatenation complete."