How to find and replace text within ".." using bash script-CodePudding

I want to replace this line #discovery.seed_hosts: ["host1","host2"] with discovery.seed_hosts: ["${extraNode1}","${extraNode2}","${masterIP}"]. Need to remove the # and replace the host1 and host2 as per the given argument also need to add another value (3rd value) into the array as well.

sudo sed -i "/#discovery.seed_hosts: ["host1","host2"]/s/#discovery.seed_hosts: ["host1","host2"]/discovery.seed_hosts: ["${extraNode1}","${extraNode2}","${masterIP}"]/" check.yml

I tried the above command to do this but it is giving error because of the ["host1","host2"] in the command.

sed: -e expression #1, char 49: Invalid range end - Error received

CodePudding user response：

You need to use the s (substitute) command, and escape ., in addition to [. Like this:

sudo sed -i 's/#\(discovery\.seed_hosts: \["\)host1","host2"]/\1${extraNode1}","${extraNode2}","${masterIP}"]/' check.yml

If you don't scape the ., the sed command will match any character where the . is, like #discovery7seed_hosts: ["host1","host2"].

The sed command is pretty straight forward. I just added parentheses around the part of the match that I wanted to reuse in the substitution which creates a group. The \1 is replace with "group 1", the contents of what's in between the parentheses, which must be escaped too.

EDIT: The ", double quotes, don't need to be escaped because the sed command is in single quotes: 's/.../.../'. Also, the ], closing square bracket, doesn't need to be escaped as long as its corresponding [, opening square bracket, has been escaped. Finally, both parentheses ( and ) need to be escaped to create the group. (END OF EDIT)

Test:

$ cat check.yml 
This is a test
Another line
#discovery.seed_hosts: ["host1","host2"]
#discovery7seed_hosts: ["host1","host2"]

OK. Good bye?
$ sed 's/#\(discovery\.seed_hosts: \["\)host1","host2"]/\1${extraNode1}","${extraNode2}","${masterIP}"]/' check.yml 
This is a test
Another line
discovery.seed_hosts: ["${extraNode1}","${extraNode2}","${masterIP}"]
#discovery7seed_hosts: ["host1","host2"]

OK. Good bye?

$

CodePudding user response：

You'll need to escape [s and "s with backslashes as:

sudo sed -i "/#discovery.seed_hosts: \[\"host1\",\"host2\"]/s/#discovery.seed_hosts: \[\"host1\",\"host2\"]/discovery.seed_hosts: [\""${extraNode1}\"",\""${extraNode2}\"",\""${masterIP}\""]/" check.yml