Perl 正则表达式详细信息

Question

There is a line $line =~ s/\\^M $// in a perl code. What does the regex s/\\^M $// mean?

Answer 1

It means if $line contains the exact sub string ^M (hat-emm-space) at the end then remove it

The reason for the initial backslash is that ^ has a special meaning in regexp and the backslash turns off the special meaning and makes it literally match

The $ is an anchor to force a match at the end of the line

Often ^M literal characters end up in files when copy paste is inappropriately used