如果在 UNIX shell 中不以时间戳开头，则将行加入上一行

Question

我有一个工具可以输出带有时间戳前缀的日志，但是日志条目可能包含换行符。我想将任何没有时间戳的行与前一行合并。

例子：

[ 2020/08/12 11:40] Success with "one line [42]"
[ 2020/08/12 11:40] Success with "two
lines [13]"
[ 2020/08/12 11:40] Success with "two lines with a twist
[19] to confuse you"
[ 2020/08/12 11:41] Failure with "one line again"

使用 awk 我可以做这样的事情来合并不以 [ 大括号开头的行：

awk -v RS="[" 'NR>1{$1=$1; print RS, $0}'

但是，您可以在上面的“twist”行中看到失败的地方。 “twist”行以 [ 开头，它不是时间戳的一部分。

有没有办法为那个时间戳前缀使用正则表达式？或者有没有更好的命令行工具来完成这个？

Answer 1

您能否尝试使用现场展示的样本进行书面和测试https://ideone.com/PXVCh2

awk '
{
  printf("%s%s",$0~/^\[ [0-9]{4}\/[0-9]{2}\/[0-9]{2}/\
          ?(FNR!=1?ORS:""):OFS,$0)
}
END{ print "" }
' Input_file

根据 Ed sir 的评论，添加了一个 print new line 语句以在 Input_file 的最后添加一个新行，以防万一它已经这样做了，那么可以省略该部分。

注意：我是在手机上写的；抱歉，我无法判断它在大屏幕上的显示效果如何，所以我在这里将一条打印线分成两行

Answer 2

在我看来，你真正的问题实际上是你引用的字符串可以包含换行符，所以这个寻找引用字符串的 GNU awk 解决方案（用于多字符 RS）可能比在开头查找时间戳更健壮行：

$ awk -v RS='"[^"]*"' '{gsub("\n"," ",RT); ORS=RT} 1' file
[ 2020/08/12 11:40] Success with "one line [42]"
[ 2020/08/12 11:40] Success with "two lines [13]"
[ 2020/08/12 11:40] Success with "two lines with a twist [19] to confuse you"
[ 2020/08/12 11:41] Failure with "one line again"

如果您引用的字符串可以包含可能出现在行首的时间戳，那么这将比检查以时间戳开头的行更好，例如（注意"four lines with a twist... 块中的时间戳）：

$ cat file
[ 2020/08/12 11:40] Success with "one line [42]"
[ 2020/08/12 11:40] Success with "two
lines [13]"
[ 2020/08/12 11:40] Success with "four lines with a twist
[ 2020/08/12 11:40] to confuse you
repeatedly and
in ""horrible"" ways"
[ 2020/08/12 11:41] Failure with "one line again"

.

$ awk -v RS='"[^"]*"' '{ORS=gensub("\n"," ","g",RT)} 1' file
[ 2020/08/12 11:40] Success with "one line [42]"
[ 2020/08/12 11:40] Success with "two lines [13]"
[ 2020/08/12 11:40] Success with "four lines with a twist [ 2020/08/12 11:40] to confuse you repeatedly and in ""horrible"" ways"
[ 2020/08/12 11:41] Failure with "one line again"

Answer 3

假设日志包含您的示例文件：

$ cat log

[ 2020/08/12 11:40] Success with "one line [42]"
[ 2020/08/12 11:40] Success with "two
lines [13]"
[ 2020/08/12 11:40] Success with "two lines with a twist
[19] to confuse you"
[ 2020/08/12 11:41] Failure with "one line again"

以下代码检查双引号 (") 的数量，如果只找到一个双引号，则连接两行：

$ gawk 'gsub("\"", "\"") == 1 {x=$0; getline; print x " " $0;} gsub("\"", "\"") == 2 {print}' log

[ 2020/08/12 11:40] Success with "one line [42]"
[ 2020/08/12 11:40] Success with "two lines [13]"
[ 2020/08/12 11:40] Success with "two lines with a twist [19] to confuse you"
[ 2020/08/12 11:41] Failure with "one line again"