Shell脚本需求：提取文件名日期并校验是否未早于前两天

Let's break this down step by step to solve your date validation problem. First, note that your initial awk command only works for the first two filenames—we'll need a more flexible way to extract dates from both formats (MMDDYYYY and MM_DD_YY) in your file list. Then we'll convert those dates to a comparable format, calculate the cutoff date (two days ago), and validate each file.

Step 1: Extract & Standardize Dates from Filenames #

We'll use a Bash loop with regex matching to handle both date formats, then convert each date to a Unix timestamp (a numeric representation of time that's easy to compare).

# Initialize an associative array to store filenames and their timestamps
declare -A file_dates

# Process each filename in FFS_FILES.txt
while read -r filename; do
    # Case 1: Match MMDDYYYY format (e.g., 10262017)
    if [[ $filename =~ ([0-9]{8}) ]]; then
        raw_date="${BASH_REMATCH[1]}"
        # Rearrange to MM/DD/YYYY for date command parsing
        formatted_date="${raw_date:0:2}/${raw_date:2:2}/${raw_date:4:4}"
    
    # Case 2: Match MM_DD_YY format (e.g., 10_22_17)
    elif [[ $filename =~ ([0-9]{2})_([0-9]{2})_([0-9]{2}) ]]; then
        month="${BASH_REMATCH[1]}"
        day="${BASH_REMATCH[2]}"
        year="20${BASH_REMATCH[3]}" # Assume 20xx for two-digit years
        formatted_date="${month}/${day}/${year}"
    
    # Handle files where date can't be extracted
    else
        echo "⚠️ Warning: No valid date found in filename: $filename"
        continue
    fi

    # Convert formatted date to Unix timestamp (silence invalid date errors)
    file_timestamp=$(date -d "$formatted_date" +%s 2>/dev/null)
    if [[ -z $file_timestamp ]]; then
        echo "❌ Error: Invalid date '$formatted_date' from filename: $filename"
        continue
    fi

    # Store the timestamp with its filename
    file_dates["$filename"]=$file_timestamp
done < FFS_FILES.txt

Step 2: Calculate the Cutoff Timestamp (Two Days Ago) #

Use the date command to get the Unix timestamp for exactly two days before the current date:

# Get timestamp for 2 days ago (adjust timezone if needed with TZ=UTC)
two_days_ago_ts=$(date -d "2 days ago" +%s)

Step 3: Validate Each File's Date #

Loop through our associative array and compare each file's timestamp against the cutoff:

echo -e "\n📋 Validation Results:"
for filename in "${!file_dates[@]}"; do
    file_ts=${file_dates[$filename]}
    if [[ $file_ts -lt $two_days_ago_ts ]]; then
        echo "❌ FAIL: $filename (date is earlier than two days ago)"
    else
        echo "✅ PASS: $filename (date is valid)"
    fi
done

Key Notes: #

• Timezone Considerations: If your files use UTC dates, add TZ=UTC before the date commands (e.g., TZ=UTC date -d ...) to avoid timezone mismatches.
• Year Assumption: For two-digit years (17), we assume 2017—adjust the year="20${BASH_REMATCH[3]}" line if you need to handle 19xx years.
• Flexibility: This script handles both date formats in your example, and you can extend the regex patterns if you encounter other date formats later.

内容的提问来源于stack exchange，提问作者kunal .Gaurav