How to replace single line in the text file with bash?

Question

I would like to replace one (first line) in app.yaml file I have with bash. The file looks like below:

application: my-appid
version: 1
...

my-appid there should be replaced with my-appid2 .

I tried to use

sed -i.bak -e "s/application: \.*/application: \ 2/" app.yaml

but in result I get application: 2my-appid .

How should I fix it? (my-appid shouldn't be hardcoded)

Answer 1

sed -i.bak -e 's/application: .*/&2/' app.yaml

&在替换中替换为与regexp匹配的所有内容。

Answer 2

sed -i.bak -e '1s/ .*/ my-appid2/' app.yaml

在第1行中，将一个空格替换为任何内容，并以一个空格替换您的新应用名称。