CODEWITHSUNDEEP
bashsed
Debabrata Roy
Debabrata Roy

Reputation: 187

In sed how do I select a range between a pair of patterns only?

Let + and - be the patterns and say the file is the following:

+
-
some lines 1
-
some lines 2
+
some lines 3
-
+
some lines 4

If we were specify a range in sed, say so: sed -n /+/,/-/ p it would end up printing:

+
-
+
some lines 3
-
+
some lines 4

While the rest of it is alright, how do I not select some lines 4 as it clearly isn't in between a pair of patterns.

Edit: There can be multiple lines between the + and - symbols. Also, it's not an option to remove all the lines following the last - prior to running this particular sed statement. Please keep in mind that this is a very generalized and reduced problem statement. I only need to know if there's a way to accomplish this is sed. It's hardly even snippet in the rest of the source, so anyone assuming I am out to get you to do my job, understand that that's not my intention.

Upvotes: 0

Views: 113

Answers (2)

potong
potong

Reputation: 58351

This might work for you (GNU sed):

sed -n '/^+/{:a;N;/^-/M!ba;p}' file

Use seds grep-like switch -n. Gather up lines between start and end tokens and then explicitly print them. All other lines will not be printed.

Upvotes: 0

Cyrus
Cyrus

Reputation: 88553

Save lines from + to - to GNU sed's hold space and only copy hold space back to pattern space if current line contains -.

sed -n '/+/,/-/{ /+/{h;b}; H; /-/{g;p} }' file

Output:

+
-
+
some lines 3
-

Upvotes: 1

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