如何在Bash脚本中实现文件名按指定长度截断功能？

Alright, let's get that filename truncation feature working for option 3 of your script. The core goal is to split each filename into its base name and extension, truncate the base to your specified length, then stitch them back together. Here's a robust implementation you can drop right into your existing framework:

Step 1: Add the Truncation Logic to Option 3 #

In your script's case statement where option 3 is handled, replace the placeholder with this code:

3)
    read -p "Enter the desired truncation length: " trunc_len
    # Validate input is a positive integer (no zeros or non-numeric values)
    if ! [[ "$trunc_len" =~ ^[1-9][0-9]*$ ]]; then
        echo "Error: Please enter a valid positive integer."
        break
    fi

    # Loop through all regular files in the current directory (skip folders)
    for file in *; do
        if [[ -f "$file" ]]; then
            # Split filename into base name and extension
            base_name="${file%.*}"
            file_ext="${file##*.}"

            # Handle files with no extension
            if [[ "$base_name" == "$file" ]]; then
                new_filename="${base_name:0:$trunc_len}"
            else
                new_filename="${base_name:0:$trunc_len}.$file_ext"
            fi

            # Skip renaming if the truncated name matches the original
            if [[ "$new_filename" != "$file" ]]; then
                # Optional: Avoid overwriting existing files with duplicate truncated names
                counter=1
                temp_name="$new_filename"
                while [[ -e "$temp_name" ]]; do
                    temp_name="${base_name:0:$trunc_len}_$counter.$file_ext"
                    ((counter++))
                done
                mv -v "$file" "$temp_name"
            fi
        fi
    done
    echo "Filename truncation completed successfully!"
    ;;

Step 2: Breakdown of the Key Logic #

Let's walk through what each part does to make sure you understand:

• Input Validation: We check that the user enters a positive integer to prevent invalid truncation lengths (like 0 or letters).
• File Filtering: The -f "$file" check ensures we only modify regular files, not directories or symlinks.
• Splitting Filenames:
  • ${file%.*} removes the shortest suffix starting with . to get the base name (e.g., Adsbgnyr.txt → Adsbgnyr).
  • ${file##*.} removes the longest prefix ending with . to get the extension (e.g., Adsbgnyr.txt → txt).
• No-Extension Handling: If the base name matches the original file, that means there's no extension—we just truncate the full name directly.
• Duplicate Protection: The counter adds a suffix (like _1, _2) if multiple files truncate to the same name, so you don't accidentally overwrite existing files.

Step 3: Test It Out #

Create a few test files to verify the functionality:

touch Adsbgnyr.txt HelloWorld.pdf MySuperLongFilename NoExtensionTest

Run your script, select option 3, enter 3, and you'll see:

• Adsbgnyr.txt → Ads.txt
• HelloWorld.pdf → Hel.pdf
• MySuperLongFilename → MyS
• NoExtensionTest → NoE

This implementation is flexible, handles edge cases, and integrates seamlessly with your existing script structure.

内容的提问来源于stack exchange，提问作者Max The Not So Smart