新文件中的下一行以逗号分隔的单词

Question

我有一个像这样的输入文件（input.txt）：

Main1 one,two,three,four 
Main2 five,six,seven,eight 

我想要在输出文件（output.txt）中得到这样的输出：

Main1 one
Main1 two
Main1 three
Main1 four

Main2 five
Main2 six
Main2 seven
Main3 eight

Answer 1

awk '{ split($2,a,","); for (i in a) print $1, a[i]; }' input.txt

例子：

~) $ echo -e "Main1 one,two,th\nMain2 five,six,seven,eight " | awk '{ split($2,a,","); for (i in a) print $1, a[i]; }'
Main1 one
Main1 two
Main1 th
Main2 five
Main2 six
Main2 seven
Main2 eight

Answer 2

以下是一些选择：

1. 壳

   while read main rest; do 
       for i in ${rest//,/$'\n'}; do 
           echo $main $i
       done
    done < file 
   

2. Perl

   perl -lane 'print "$F[0] $_" for split(/,/,$F[1])' file
   

3. awk

   awk -F'[, ]' '{for(i=2;i<=NF;i++){print $1,$i}}' file