区分大小写:

echo ",dog,cat,dog,bird,fish," | tr ',' '\n' | grep -v '^$' | sort | uniq -c | sort -k 1,1nr

不区分大小写 :

echo ",dog,DOG,cat,dog,bird,fish," | tr ',' '\n' | grep -v '^$' | sort -rf | uniq -ci | sort -k 1,1nr

执行反向排序( -r )并且不区分大小写,在大写字母后面加上小写字母。那么 uniq -i . (您可能需要确保定义的排序规则 LC_COLLATE 可能是像这样的地方 LANG 和 LC_ALL 没有影响 sort 行为)。

然后检查第一行中的数字是否为>1

使用

$ .\script.sh ,dog,dog,cat,

#!/bin/sh

num_duplicated() {
    echo $1 |
    tr ',' '\n' | # Split each items into its own line
    tr '[:upper:]' '[:lower:]' | # Convert everything to lowercase
    sort | # Sorts the lines (required for the call to `uniq`
    uniq -d | # Passing the `-d` flag to show only duplicated lines
    grep -v '^$' | # Passing `-v` on the pattern `^$` to remove empty lines
    wc -l # Count the number of duplicate lines
}

main() {
    num_duplicates=$(num_duplicated "$1") 
    if [[ $num_duplicates -eq '0' ]]
    then
        echo "No duplicates"
    else
        echo "Contains duplicate(s)"
    fi
}

main $1