Replacing a string with quotes selectively using sed

Question

I have a file.

$ cat file
"bar":  false
"foo":  false

I need to replace the word false with true only in the pattern "foo": false. The problem is quotes and spaces.

I thought about two ways:

1. To isolate the whole pattern in some sort of qoutes/double quotes.
2. To replace only such "false" which has a "foo" before it.

An example try of 2 option:

$ sed -i 's/\(.*foo\)/false/true\1/g' file

It failed.

Solution

Use an address. The quotes are not a problem if you single quote your sed expression

$ sed '/"foo"/ s/false/true/' file
"bar":  false
"foo":  true

If you really need to match the whole pattern, fine:

$ sed '/"foo": *false/ s/false/true/' file
"bar":  false
"foo":  true

* matches any number of the preceding character (space).

You can use \s to also match tabs (any horizontal whitespace):

sed '/"foo":\s*false/ s/false/true/' file

Add the -i option after testing to modify the original file.

Comments

[Zanna]

Most welcome, thanks for asking :) @JosefKlimuk