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I have currently a set of seds that's working well except for one thing.

The particular expression I'm having an issue with is:

sed -i '/[^}.to]\.to[[:space:]]/ s/\(\S\)/expect(\1/' ../_spec_seded/"$file"

Right now this works fine.
Basically it looks for .to and insert expect at the start of the expression. In particular, it excludes }.to when looking to match on .to which works.

Now I want to also exclude 'this' or 'that' from the search match. In my case }.to or

i.e. instead of


should I have:


would I even need to escape parens if using them like


or even the | as well?


I'm trying to make the match work on: do thing
stuff).to do thing that do  # Note this edge case! (pretend contains "end"!) 

but not on

this will be here }.to do
last.end}.to do
all.this at the
none at


all.this at the # i.e. no spaces before as it is the start of the line.

Negating with OR's generally (all languages) seems tricky (due to false positives).

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What's the difference between the and none at cases that one should match and the other shouldn't? And how come matches when it doesn't have a \.to[[:space:]]? – Joseph R. Nov 10 '13 at 19:46

2 Answers 2

up vote 2 down vote accepted

Pending your response to my comment on the question, here's my answer:

  • First of all, [^}.to] doesn't do what you seem to think. It will not match lines that don't have the pattern }.to. It matches lines that have any character other than ., }, t or o. In other words, many lines.

  • To make things easier, let's have sed print nothing by default then tell it to print everything except those lines matching the patterns you want to exclude:

    sed -n '/\(\bend\|}\.to\)/!p' your_file

This will print all lines not containing at a word boundary (i.e. doesn't count) or }.to.

If, in addition you want to print only those lines that match \.foo[[:space:]], simply delete lines matching unwanted patterns and add a conditional print:

sed -n '/\(\bend\|}\.to\)/d;/\.to[[:space:]]/p' your_file

Of course, between the match and the print, you can apply whatever substitution you feel like:

sed -n '/\(\bend\|}\.to\)/d;/\.to[[:space:]]/s/foo/bar/g;p' your_file
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Thanks Joseph, good info. – Michael Durrant Nov 10 '13 at 20:39

For most cases this seems to work:


sed -i 's/[^}.to].to[[:space:]]/).to /' ../_spec_seded/"$file"


sed -i 's/[^}.to|].to[[:space:]]/).to /' ../_spec_seded/"$file"
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