How to add to the end of lines containing a pattern with sed or awk?

Question

Here is example file:

somestuff... all: thing otherthing some other stuff 

What I want to do is to add to the line that starts with all: like this:

somestuff... all: thing otherthing anotherthing some other stuff 

Answer 1

This works for me

sed '/^all:/ s/$/ anotherthing/' file 

The first part is a pattern to find and the second part is an ordinary sed's substitution using $ for the end of a line.

If you want to change the file during the process, use -i option

sed -i '/^all:/ s/$/ anotherthing/' file 

Or you can redirect it to another file

sed '/^all:/ s/$/ anotherthing/' file > output 

Answer 2

You can append the text to $0 in awk if it matches the condition:

awk '/^all:/ {$0=$0" anotherthing"} 1' file 

Explanation

• /patt/ {...} if the line matches the pattern given by patt, then perform the actions described within {}.
• In this case: /^all:/ {$0=$0" anotherthing"} if the line starts (represented by ^) with all:, then append anotherthing to the line.
• 1 as a true condition, triggers the default action of awk: print the current line (print $0). This will happen always, so it will either print the original line or the modified one.

Test

For your given input it returns:

somestuff... all: thing otherthing anotherthing some other stuff 

Note you could also provide the text to append in a variable:

$ awk -v mytext=" EXTRA TEXT" '/^all:/ {$0=$0mytext} 1' file somestuff... all: thing otherthing EXTRA TEXT some other stuff