使用sed将^ [（s3B替换为空白

Question

I'm trying to use sed with perl to replace ^[(s3B with an empty string in several files.

s/^[(s3B// isn't working though, so I'm wondering what else I could try.

Answer 1

You need to quote the special characters:

 $ echo "^[(s3B AAA ^[(s3B"|sed 's/\^\[[(]s3B//g'
  AAA 

 $ echo "^[(s3B AAA ^[(s3B" >file.txt
 $ perl -p -i -e 's/\^\[[(]s3B//g' file.txt      
 $ cat file.txt 
  AAA 

Answer 2

The problem is that there are several characters that have a special meaning in regular expressions. ^ is a start-of-line anchor, [ opens a character class, and ( opens a capture.

You can escape all non-alphanumerics in a Perl string by preceding it with \\Q , so you can safely use

s/\Q^[(s3B//

which is equivalent to, and more readable than

s/\^\[\(s3B//

Answer 3

If you're dealing with ANSI sequences (xterm color sequences, escape sequences), then ^[ is not '^' followed by '[' but rather an unprintable character ESC, ASCII code 0x1B.

To put that character into a sed expression you need to use \\x1B in GNU sed, or see http://www.cyberciti.biz/faq/unix-linux-sed-ascii-control-codes-nonprintable/ . You can also insert special characters directly into your command line using ctrl+v in Bash line editing.

Answer 4

In regex "^", "[" and "(" (and many others) are special characters used for special regex features, if you are referencing the characters themselves you should preceed them with "\\". The correct substitution reges would be:

$string =~ s/\^\[\(3B//g

if you want to replace all occurences.