Linux Bash Scripting: How to combine two lines by removing newline character using sed

In this post we will see how to remove the newline character and combine two lines in a text file using "sed".

In sed, we have single line version and multi-line version of few commands. One such command is the next command. Click here to see an example for single-line version of next command in sed.

You might want to look at :

How to remove a blank line after a particular line using sed

The processing space of the sed editor is known as the pattern space. The multi-line next command (N) adds the next line to the existing pattern space which already contains the previous line. So, the sed editor can treat two lines as a single line. Below is an example for the N command.

$ cat sample.txt This is the header line. This is the first line. This is the second line. This is the last line. $ $ sed ‘/first/{ N ; s/\n/ / }’ sample.txt This is the header line. This is the first line. This is the second line. This is the last line. $  

The above sed editor script searches for the line of text that contains the word “first” in it. When it finds the line, it uses the N command to combine the next line with that line. It then uses the substitution command (s) to replace the newline character with a space. The result is that the two lines in the text file appear as one line in the sed editor output.