用bash脚本批量修改文件名称（二）

前言：在上一篇文章中，我使用了warp模拟终端，让它教我写bash脚本来批量修改文件文称。这一篇则是优化，在保留文件扩展名的同时；根据文件数量，设置新文件名的对齐位（也就是有几十个文件时，从01开始编号；几百个文件时，则是从001开始。）；并且可以选择是否添加前缀。
执行时输入“./rename.sh /path/files optional_prefix”即可，如果不需要前缀，最后一个参数改成noprefix即可。代码如下：

#!/bin/bash
# Change the file name accroding to the original order by digits
# while preserving the file extension.

# Check before running: Need 3 arguments to run the script properly
if [[ $# -lt 2 ]]; then
    echo "Didn't run, because the number of argument needs to be 2"
    echo "EX: $0 [/path/to/file] [new_name_prefix]"
    exit 0
fi

# 1. Get the old name files's directory and enter it
directory=$1
cd "$1"

# 2. Set the new name prefix
prefix=$2

# 3. Count the number of files in the directory
file_count=$(($(ls -l | grep -v '^d' | wc -l) -1))
echo "The total number of files to change name is $file_count."

# 4. Get the length of file_count
bits=${#file_count}
echo "The aligned number of the new name would be $bits."

# 5. Set the starting number
starting_number=1

# 6. Change to the new file name
if [ "$2" = "noprefix" ]; then
    # Loop through each file in the directory and rename without prefix
    for file in "$directory"/*; do

        # Get the current file name (basename is a command in shell)
        current_name=$(basename "$file")

        # Get the file extension
        extension="${current_name##*.}"

        # Generate the new file name
        new_name="$(printf "%0${bits}d"  "$starting_number").${extension}"

        # Rename the file
        mv "$file" "$directory/$new_name"

        ((starting_number++))
    done
else
    # Loop through each file in the directory and rename with prefix
    for file in "$directory"/*; do
    
        # Get the current file name
        current_name=$(basename "$file")
    
        # Get the file extension
        extension="${current_name##*.}"
    
        # Generate the new file name
        new_name="${prefix}-$(printf "%0${bits}d"  "$starting_number").${extension}"
    
        # Rename the file
        mv "$file" "$directory/$new_name"
    
        ((starting_number++))
    done
fi
echo "Complete. And the first 10 file is: $(ls | head -10)"
exit 0