Delete lines of text with sed

Delete each matching line#

Probably the simplest case is to delete each line of text that matches the regex pattern.

sed '/pattern/d' input.txt

Example on sample text¹ with line numbers kept as in the original. Lines 3 and 10 deleted:

sed '/sem/d' sample.txt

 1   Lorem ipsum dolor sit amet consectetur
 2   adipiscing elit. Quisque faucibus ex
 4   In id cursus mi pretium tellus duis
 5   convallis. Tempus leo eu aenean sed
 6   diam urna tempor. Pulvinar vivamus
 7   fringilla lacus nec metus bibendum
 8   egestas. Iaculis massa nisl malesuada
 9   lacinia integer nunc posuere. Ut
11   taciti sociosqu. Ad litora torquent per
12   conubia nostra inceptos himenaeos.

Delete all lines between matching patterns#

Delete each line of text that matches the regex pattern and all lines in between them.

sed '/pattern1/,/pattern2/d' input.txt

Example on sample text¹ with line numbers kept as in the original. Lines 2 to 9 deleted:

sed '/Quisque/,/posuere/d' sample.txt

1   Lorem ipsum dolor sit amet consectetur
10  hendrerit semper vel class aptent
11  taciti sociosqu. Ad litora torquent per
12  conubia nostra inceptos himenaeos.

Delete all lines between matching patterns, excluding the patterns#

Delete each line of text between the lines that match the regex pattern, but exclude the lines with the matches.

sed '/pattern1/,/pattern/{//!d}' input.txt

The sed command {//!d} reuses the same pattern from the outside command and deletes d all lines that do not match ! the pattern. Example on sample text¹ with line numbers kept as in the original. Lines 3 to 8 deleted:

sed '/Quisque/,/posuere/{//!d}' sample.text

1   Lorem ipsum dolor sit amet consectetur
2   adipiscing elit. Quisque faucibus ex
9   lacinia integer nunc posuere. Ut
10  hendrerit semper vel class aptent
11  taciti sociosqu. Ad litora torquent per
12  conubia nostra inceptos himenaeos.

More complex sed operations

Complex operations in sed can be used in the previous examples as well. The delete command d can be replaced by any other sequence of sed commands. Example replacing all lines in between the matching pattern with the text PLACEHOLDER:

sed '/Quisque/,/posuere/{//!s|.*|PLACEHOLDER|}' sample.text

Footnotes#

1. Sample text

   1 Lorem ipsum dolor sit amet consectetur

   2 adipiscing elit. Quisque faucibus ex

   3 sapien vitae pellentesque sem placerat.

   4 In id cursus mi pretium tellus duis

   5 convallis. Tempus leo eu aenean sed

   6 diam urna tempor. Pulvinar vivamus

   7 fringilla lacus nec metus bibendum

   8 egestas. Iaculis massa nisl malesuada

   9 lacinia integer nunc posuere. Ut

   10 hendrerit semper vel class aptent

   11 taciti sociosqu. Ad litora torquent per

   12 conubia nostra inceptos himenaeos. ↩ ↩² ↩³