Using sed to delete all lines between two matching patterns

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Use this sed command to achieve that:

sed '/^#/,/^\$/{/^#/!{/^\$/!d}}' file.txt

Mac users (to prevent extra characters at the end of d command error) need to add semicolons before the closing brackets

sed '/^#/,/^\$/{/^#/!{/^\$/!d;};}' file.txt

OUTPUT

# ID 1
$ description 1
blah blah
# ID 2
$ description 2
blah blah
blah blah

Explanation:

  • /^#/,/^\$/ will match all the text between lines starting with # to lines starting with $. ^ is used for start of line character. $ is a special character so needs to be escaped.
  • /^#/! means do following if start of line is not #
  • /^$/! means do following if start of line is not $
  • d means delete

So overall it is first matching all the lines from ^# to ^\$ then from those matched lines finding lines that don’t match ^# and don’t match ^\$ and deleting them using d.

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