how to change a specific line in the linux command

Question

how do i change this text for a specific line

Suppose I want to change line 50, and I want to change 8 letters after "user": like the example below which I bold

line 50 "user": " 9077c266 -8944-11eb-a9d1-fa163e4be1a2"

Answer 1

Use the s command in sed to search and replace.

sed -i 'Ns/9077c266/replacement-line/' file.txt

where N should be replaced by your target line number.

To save the changed text in a different file, drop the -i option:

sed  'Ns/9077c266/replacement-line/' file.txt > new_file.txt

Answer 2

I would used sed either by line number or just content if it's unique:

sed -i '50s/9077c266/replacement/' file.txt

or:

sed -i 's/9077c266/replacement/' file.txt