Question

我想使用sed删除文本文件中的所有注释。假设评论从“A”字符开始，以新行字符结束。我想删除从“A”到行尾的所有内容，包括换行符。但是，我不想删除从“AA”开始的评论。

示例输入：

%% comment to do not delete
% comment to delete
% another comment to delte
%% comment to do not delete
Some text % comment to delete
and some more text %% comment to do not delete

期望的输出：

%% comment to do not delete
%% comment to do not delete
Some text and some more text %% comment to do not delete

Answer 1

尝试这样做：

$ perl -pe '/^[^%]*%%/ && next; s/%.*\n//g' file.txt

输出

%% comment to do not delete
%% comment to do not delete
Some text and some more text %% comment to do not delete

注意

如果您需要就地更改文件，请添加-i开关（在测试后），以便：

$ perl -i -pe '/^[^%]*%%/ && next; s/%.*\n//g' file.txt

感谢scrutinizer的贡献。

Answer 2

完美应用perl的负面后视断言：

perl -pe 's/(?<!%)%(?!%).*$//s' << END
%% comment to do not delete
% comment to delete
% another comment to delte
%% comment to do not delete
Some text % comment to delete
and some more text %% comment to do not delete
END

输出

%% comment to do not delete
%% comment to do not delete
Some text and some more text %% comment to do not delete

s标志确保点将与换行符匹配，以按要求实现“换行”。

这种正则表达式匹配可能会导致您遇到问题，例如，如果您有像

这样的行

The date is `date +%Y%m%d` % this is a comment

你最终会得到

The date is `date +

如果您的实际评论需要周围的空白，您可以使用此正则表达式：

(^| )%( .*|)$

表示

行的开头或空格
后跟注释char
后跟（一个空格和零个或多个字符）或没有
后面是行尾

Answer 3

也许这就是：

第二次更新

$ sed -e '/^%[^%]/d' -e 's/ %[^%]*$/@/' -e :a -e '/@/N; s/\n//; ta' input | sed 's/@/ /g'
%% comment to do not delete
%% comment to do not delete
Some text and some more text %% comment to do not delete

Answer 4

编辑添加了更改，以便在文件的最后一行正常运行... 尝试：

sed -e :a -e '/^[^%]*%%/n; /%/{s/%.*//; N; s/\n//;};ta' file

使用输入测试：

%% comment to do not delete
% comment to delete
% another comment to delte
%
%% comment to do not delete
Some text % comment to delete
Some more text % more comment to delete
and some more text %% comment to do not delete
fdgdfgdgdgd %
gfdgd
some text followed by %% comment to not delete that contains a % somewhere
some text followed by % comment to delete that contains %% somewhere
hello there

输出：

%% comment to do not delete
%% comment to do not delete
Some text Some more text and some more text %% comment to do not delete
fdgdfgdgdgd gfdgd
some text followed by %% comment to not delete that contains a % somewhere
some text followed by hello there

Answer 5

使用带有Sed的表达式顺序

使用sed，指令的顺序可能很重要。例如：

$ sed -ne '/^% /d; /[^%]%.*/ {s/%.*//; n}; p' /tmp/corpus 
%% comment to do not delete
%% comment to do not delete
and some more text %% comment to do not delete

在此示例中，sed脚本按此顺序执行其任务：

抑制输出。
删除以百分号开头的行。
使用替换从一个百分比中删除所有字符到行尾，然后将下一行附加到模式空间而不换行。
打印图案空间。

此脚本适用于您在问题中提供的语料库。不保证在没有修改的情况下与任何其他语料库一起使用，如果您附加到模式空间的行包含注释字符，则显然不起作用。

使用sed删除内联注释

5 个答案:

输出

注意

使用带有Sed的表达式顺序