不要使用shell读取循环，参见why-is-using-a-shell-loop-to-process-text-considered-bad-practice，只需一个awk脚本就可以运行得更快，更可移植，更容易编写（例如-您目前有2个使用shell读取循环的答案，如果“type”包含空白，则两个答案都会失败，如果输入包含任何反斜杠，其中一个也会失败），例如使用任何awk：

$ cat tst.sh
#!/usr/bin/env bash

# define the name of the input file
input_file="plants.tsv"

# define the name of the output file
output_file="normalized_plants.tsv"

# define the index of the list column (counting from 1)
list_column=2

awk -v list_column="$list_column" '
    BEGIN { FS=OFS="\t" }
    {
        n = split($list_column,names,",")
        for ( i=1; i<=n; i++ ) {
            print $1, names[i]
        }
    }
' "$input_file" > "$output_file"

$ ./tst.sh

$ cat normalized_plants.tsv
TYPE    NAME
Fruit   apple
Fruit   strawberry
Vegetable       potato

我使用for ( i=1; i<=n; i++ )而不是上面的for ( i in names )，以保证输入中的名称顺序在输出中得到保留，请参阅https://www.gnu.org/software/gawk/manual/gawk.html#Scanning-an-Array。

这个答案只是告诉你，你的脚本使用纯bash可以压缩为：

#!/bin/bash

while read -r type names; do
    echo "$type"$'\t'"${names//,/$'\n'$type$'\t'}"
done < plants.tsv > normalized_plants.tsv

通常情况下，awk解决方案应该是首选。

bash：

while read type name_list; do                # Read the 2 fields in type and name_list
    readarray -d, -t names <<< "$name_list," # Split the name_list by comma and save it in names array.
    unset names[-1]                          # This line is only to remove the tailing newline for the last entry.
    for name in "${names[@]}"; do            # For each name, ...
        echo "$type $name"                   # ... print type and name
    done
done < plants.tsv > output_plants.tsv        # Input, output file redirection.

awk版本：

awk '{split($2, s, ","); for(i in s){print $1, s[i]}}' plants.tsv > output_plants.tsv

只是为了多样化，一个简单的字符串处理解决方案与sed。

$: sed -E ':x ; s/^([^[:space:]]+)[[:space:]]+([^,]+),/\1\t\2\n\1\t/; t;' file
TYPE  NAME
Fruit   apple
Fruit   strawberry
Vegetable  potato

使用给定的简单文件。确保您确认任何更复杂的文件。

echo '
TYPE  NAME  
Fruit  apple,strawberry,banana
Vegetable  potato' |

mawk 'NR==!_ || $NF!~/,/ || gsub(",[^,]+", "\n"$!_ " &", $NF) + gsub(",",_)'

TYPE  NAME  
Fruit apple
Fruit strawberry
Fruit banana
Vegetable  potato

如果你想对输出间隔的差距吹毛求疵，那么

gawk 'NR==!_ ? OFS = substr($_, match($_, "[ \t]+"),RLENGTH) \
             : $NF!~/,/ || gsub(",[^,]+", "\n" $!_ OFS "&", $NF) gsub(",",_)'

TYPE  NAME  
Fruit  apple
Fruit  strawberry
Fruit  banana
Vegetable  potato