如何将公共前缀重写为标头？

Question

假设您有一个如下所示的变更注释列表：

2011-02-21: Removed first feature to get rid of previous customer
2011-02-21: Added second feature to open up new markets
2011-02-09: Implemented hot fix to calm down angry customer
2011-02-08: Developed project into a minimal viable product
2011-02-08: Started project

可以使用标准 shell 工具将其重写为以下格式吗？

2011-02-21
  * Removed first feature to get rid of previous customer
  * Added second feature to open up new markets

2011-02-09
  * Implemented hot fix to calm down angry customer

2011-02-08
  * Developed project into a minimal viable product
  * Started project

如果是这样，怎么办？

Answer 1

通过这个管道。

#!/bin/bash

lastprefix=""
while read prefix line
do
  if [ "$prefix" != "$lastprefix" ]
  then
    lastprefix="$prefix";
    echo ""
    echo "$prefix"
  fi
  echo "  *  $line"
done

Answer 2

这应该可以做到：

awk -F: '$1 != prev {print $1; prev = $1} {$1 = ""; print "  *" $0}' inputfile