sed tutorial: sed insert line before match

Sed insert a line before match, you can use the sed function: i, add a new line before the matched string.

syntax

➜  sed '/option/i newLine' file       #option: matched content
➜  sed 'ni newLine' file              #n: line number
➜  sed '$i newLine' file              #$: last line

examples

Adding new lines before matching content is similar to adding new lines after matching content, using the sed function: i.

In the following example, we will use the sed i function to add a new line before the matched content.

Add a new line before the line containing the string “hello“:

➜  ~ sed '/hello/ised add a new line' test.log

Insert a new line before the first line:

➜  ~ sed '1ised add a new line' test.log

Insert a new line before the last line:

➜  ~ sed '$ised add a new line' test.log
this is a test file.
hello
apple
watch
sed add a new line
world

Insert a new line before each line:

➜  ~ sed '/$/i sed add a new line' test.log