如何在AWK中填充CSV格式的空單元格？

Question

我有一個CSV文件這樣，用@作爲分隔符：

Chapter 1@This is some text. 
     @This is some more text. 
     @This is yet some more text. 
Chapter 2@This is some text. 
     @This is some more text. 
     @This is yet some more text. 

第一列包含章節編號。第二欄包含本章的內容。

我需要填寫A列中的所有章節編號，以便下面的任何空單元格都填入章節編號。例如，輸出爲：

Chapter 1@This is some text. 
Chapter 1@This is some more text. 
Chapter 1@This is yet some more text. 
Chapter 2@This is some text. 
Chapter 2@This is some more text. 
Chapter 2@This is yet some more text. 

如何填滿表格A列中的所有空單元格？

Answer 1

您可以使用awk這樣的：

awk 'BEGIN{FS=OFS="@"} {if ($1 ~ /^[ \t]*$/) $1=ch; else ch=$1} 1' file 

Chapter 1@This is some text. 
Chapter 1@This is some more text. 
Chapter 1@This is yet some more text. 
Chapter 2@This is some text. 
Chapter 2@This is some more text. 
Chapter 2@This is yet some more text. 

使用簡單的regex檢查，我們確認是否$1是不是空的，然後我們設置變量CH as name of the first chapter. Then in next subsequent lines we set chapter name to the value we've stored in variable ch`。

Answer 2

使用awk

輸入

$ cat file 
Chapter 1@This is some text. 
     @This is some more text. 
     @This is yet some more text. 
Chapter 2@This is some text. 
     @This is some more text. 
     @This is yet some more text. 

輸出

$ awk 'BEGIN{FS=OFS="@"}/^[ \t]+/{$1=c}{c=$1}1' file 
Chapter 1@This is some text. 
Chapter 1@This is some more text. 
Chapter 1@This is yet some more text. 
Chapter 2@This is some text. 
Chapter 2@This is some more text. 
Chapter 2@This is yet some more text. 

$ awk 'BEGIN{FS=OFS="@"}/^[^\t ]+/{c=$1}{$1=c}1' file 
Chapter 1@This is some text. 
Chapter 1@This is some more text. 
Chapter 1@This is yet some more text. 
Chapter 2@This is some text. 
Chapter 2@This is some more text. 
Chapter 2@This is yet some more text. 

Answer 3

嘗試這種解決方案的其他方式 -

awk -F@ '$1!~/^[[:space:]]+/ {h=$1FS} {print ($1!~/^[[:space:]]+/? $0 : h$2)}' f 
Chapter 1@This is some text. 
Chapter 1@This is some more text. 
Chapter 1@This is yet some more text. 
Chapter 2@This is some text. 
Chapter 2@This is some more text. 
Chapter 2@This is yet some more text.