Command-line Knowledge Base

sed

Use a sed script/file

Ranges by patterns

You can specify two regular expressions as the range. Assuming a "#" starts a comment, you can search for a keyword, remove all comments until you see the second keyword. In this case the two keywords are "start" and "stop:"

To add text to the end of a file ^[1][2]

Using variables in sed commands ^[3]

Use double quotes to get the shell to expand variables.

Replace one or more digits [1]

Replace one or more digits [2] ^[5]

Replace newlines with a space ^[4]

Delete HTML Tags ^[6]

Simple Multiline Tag Matching

To replace:

<p>Some important paragraph text</p>
<ul>
<ul>
<ul>
<li>Some important list item</li>

With:

<p>Some important paragraph text</p>

<ul>
<li>Some important list item</li>

Use:

Delete two blank lines in a row ^[7]*

* This article does a good job of explaining how sed works. Also gives an example for deleting three blank lines in a row.

Remove the first word of a line with sed (1/2) ^{[8] [9]}

root@linux:~# echo "first second third fourth fifth" | sed "s/^[^ ]* //"
second third fourth fifth

sed 's/\(^[^ ]\)* /<p>\1/' twelve_steps__multi_purpose.html

Replace an entire line by line number

Remove a Range of Lines ¹⁰