sed how to replace the regex string

Question

I have a string like
"solrHost" : "http://localhost:8983,http://localhost:8764", in a file called sampple.json. There could be space between "solrHost" and : or maybe not, and there could be space between : and "http://localhost:8983,http://localhost:8764"

I have a another variable newServerName="http://newserver,http://newserver2"

The value of solrHost could be anything between double quotes,

I want to replace the value of solrHost from old to newServerName using sed can anyone help me here ?

Rule 1 of working with JSON: Use a tool that understands the format, like jq. — Shawn
– Shawn, Commented Dec 25, 2019 at 8:39

Shawn · Accepted Answer · 2019-12-25 08:50:45Z

2

You're much, much better off using a tool that understands JSON instead of trying to kludge together something with sed and regular expressions. jq is the go-to for command line manipulation of JSON:

$ cat foo.json
{
    "solrHost" : "http://localhost:8983,http://localhost:8764",
    "foo": 12
}
$ jq --arg url "http://newserver,http://newserver2" '.solrHost = $url' foo.json    
{
  "solrHost": "http://newserver,http://newserver2",
  "foo": 12
}

answered Dec 25, 2019 at 8:50

Shawn

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2 Comments

Shawn Over a year ago

@DavidC.Rankin I wonder if there's an answer as good as the classic "Don't use regular expressions to parse XML" one for JSON...

David C. Rankin Over a year ago

I think that covers it. But you get some quirky questions that are not json, but sure look a lot like them. Either way with those quirky json-like formatted files, you are basically playing Russian-roulette without something like jq that is format aware and will validate the results.

Jonathan Leffler · Accepted Answer · 2019-12-25 08:51:50Z

1

sed 's%\("solrHost"[[:space:]]*:[[:space:]]*\)"[^"]*"%\1"'"$newServerName"'"%'

Use single quotes around most of the script.
Use % instead of / to mark the sections of the s/// (or s%%%) command.
Use [[:space:]]* to cover zero or more characters in the space class. Replace with just a blank-star if you don't care about the alternatives (tabs, etc), which is probably justifiable with well-formed JSON.
Capture the original "solrHost" part.
Be very careful with the quotes in the replacement.
- "'"$newServerName"'"
- The first double quote will appear in the replacement text.
- The first single quote terminates the current single-quoted string.
- The second double quote starts a new double-quoted string.
- The replacement variable is next.
- The third double quote ends the double-quoted string.
- The second single quote starts a new (and rather short) single-quoted string.
- The fourth double quote will appear in the replacement text.

answered Dec 25, 2019 at 8:51

Jonathan Leffler

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2 Comments

Jonathan Leffler Over a year ago

That depends more on the layout of the fields. The chances are it would be OK, but if the JSON is on a single line, the simpler code could replace the wrong info whereas the admittedly more complex code in the answer would not make that mistake.

David C. Rankin Over a year ago

You are correct and you would definitely need the alternative substitute delimiters, e.g. sed '/^"solrHost"/s@"http.*$@'"$newServerName"'@'

RavinderSingh13 · Accepted Answer · 2019-12-25 09:01:26Z

-1

Use below sed command to replace the text .

%s/solrHost(old name)/newServerName/g

edited Dec 25, 2019 at 9:01

RavinderSingh13

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answered Dec 25, 2019 at 8:50

Nikita Bakshi

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