How to escape characters in sed

Question

I'm trying to remove some text from multiple files using sed. This is the text I'm trying to delete:

\once override TupletBracket #'stencil = ##f

I've tried this line in sed but I can't get it to work:

sed -i '' -e 's/\\once \\override TupletBracket #'stencil = ##f//g' *ily

I've tried escaping the # symbols, the ' and the = but still no joy. Could anyone please point me in the right direction?

Possible duplicate of [How to escape single quote in sed?](http://stackoverflow.com/questions/24509214/how-to-escape-single-quote-in-sed) — Benjamin W., Mar 06 '16 at 07:06

dan4thewin · Answer 1 · 2016-03-06T20:35:30.553

1

I think it's better to use single quotes here rather than double quotes to avoid the extra \s and other possible expansions (e.g. variables). Where you want a literal single quote, you close the quotation, add \', and then start a new quotation for the remainder.

$ cat in
before \once override TupletBracket #'stencil = ##f after
$ sed 's/\\once override TupletBracket #'\''stencil = ##f//g' in
before  after

edited Mar 06 '16 at 20:35

answered Mar 06 '16 at 07:16

dan4thewin

1,134
7
10

There are separate reasons for why the `\\` and `'` need to be quoted. In the first case `\\` is used to quote characters in the LHS of the substitute command and therefore must also be quoted. The `'` is part of the shell which is quoting the sed command and must be quoted first in the shell and concatenated to the command. – potong Mar 06 '16 at 09:31

score 0 · Accepted Answer · answered Mar 06 '16 at 06:40

you can't use ' directly inside sed command that is quoted using '. Use a double quotes instead and to match \ you'll need to use \\\ to have \\ i.e \.

$ sed "s/\\\once override TupletBracket #'stencil = ##f//g"
\once override TupletBracket #'stencil = ##f

hello \once override TupletBracket #'stencil = ##f xyz
hello  xyz
$

score 0 · Answer 3 · answered Mar 06 '16 at 14:37

# and = are not RE metacharacters nor do they have any other special meaning to sed within a regexp (= does outside of a regexp) unless the regexp is delimited with one of them so there's no reason to escape them in your script. ' only has significance if the whole script is delimited with 's since in shell no script that's delimited by a given character can include that character. So here's your choices:

$ echo "seab'cd" | sed 's/b'\''c/foo/'
seafood

$ echo "seab'cd" | sed "s/b'c/foo/"
seafood

Note that if you use the second (double quotes) version then you're allowing shell variables to expand inside the script and would require double-backslashes to escape chars.

I expected using the octal representation of a ' (i.e. \047) would work too like it does in awk:

$ echo "seab'cd" | awk '{sub(/b\047c/,"foo")}1'
seafood

but it didn't:

$ echo "seab'cd" | sed 's/b\047c/foo/'
seab'cd

and I suspect that's because sed is treating \0 as a backreference. It does work with the hex representation:

$ echo "seab'cd" | sed 's/b\x27c/foo/'
seafood

but that's dangerous and should be avoided (see http://awk.freeshell.org/PrintASingleQuote).

How to escape characters in sed

3 Answers3

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