如何在BASH中查找和替换文件每一行的最后一个空格？

Question

I have a file like this:

Once upon a time there lived a cat.
The cat lived in the forest.
The forest had many trees.

I need to replace the last space per line with a "@", eg:

Once upon a time there lived a@cat.
The cat lived in the@forest.
The forest had many@trees.

I tried sed 's/ .*$/@/g' file.txt , but .* matches everything and deletes all of the text found there.

How can I replace the last space per line with "@"?

Answer 1

尝试这个：

sed 's/\(.*\) /\1@/'

Answer 2

匹配最后一个空格的正则表达式，什么都不是(?=\\S+$) ，不确定如何将sed切换到PCRE模式（以支持先行）：

perl -ple "s/ (?=\S+$)/@/" file.txt

Answer 3

我通常为此使用Perl：

perl -ple 's/ ([^ ]+)$/@\1/' file.txt

Answer 4

Try

s/\s([^\s]*)$/@\1/g

Good luck, bob

EDIT: lol, tested it, seems to do what you want :)

my $s = "the quick brown fox jumped";
$s =~ s/\s([^\s]*)$/@\1/g;
print $s;
# prints the quick brown fox@jumped