find matching text and replace next line in yml - linux

Question

I'm trying to find a line in a yml configuration file and replace the next line with a specific value. I tried sed, but it seems it is not replacing or not able to find the pattern. Below is the snippit of that yml file
applicationConnectors:
- type: http
port: 14080
bindHost: 15.213.48.154
headerCacheSize: 512 bytes
outputBufferSize: 32KiB
maxRequestHeaderSize: 8KiB
maxResponseHeaderSize: 8KiB
inputBufferSize: 8KiB
idleTimeout: 30 seconds
minBufferPoolSize: 64 bytes
bufferPoolIncrement: 1KiB
maxBufferPoolSize: 64KiB
acceptorThreads: 1
selectorThreads: 2
acceptQueueSize: 1024
reuseAddress: true
useServerHeader: false
useDateHeader: true
useForwardedHeaders: true
adminConnectors:
- type: http
port: 14180
I want to change port value to 14081 for applicationConnectors as there is another port exists for adminConnectors
After the script execution it should look like:
applicationConnectors:
- type: http
port: 14081
bindHost: 15.213.48.154
headerCacheSize: 512 bytes
outputBufferSize: 32KiB
maxRequestHeaderSize: 8KiB
maxResponseHeaderSize: 8KiB
inputBufferSize: 8KiB
idleTimeout: 30 seconds
minBufferPoolSize: 64 bytes
bufferPoolIncrement: 1KiB
maxBufferPoolSize: 64KiB
acceptorThreads: 1
selectorThreads: 2
acceptQueueSize: 1024
reuseAddress: true
useServerHeader: false
useDateHeader: true
useForwardedHeaders: true
adminConnectors:
- type: http
port: 14180
I have tried below code:
var1="14081"
var2="port"
sed '/applicationConnectors:/{n;s/\($var2\).*\$/\1${var1}/}' configuration.yml > newfile
mv newfile configuration.yml
but it seems this code is not replacing anything.

Answer 1

sed is best for s/old/new, that is all. For anything else just use awk for clarity, portability, robustness, etc. Look:
$ awk -v rec='applicationConnectors' -v tag='port' -v val='14081' '
/^ [^ ]/{name=$1} name==(rec":") && $1==(tag":"){sub(/[^ ]+$/,""); $0=$0 val}
1' file
applicationConnectors:
- type: http
port: 14081
bindHost: 15.213.48.154
headerCacheSize: 512 bytes
outputBufferSize: 32KiB
maxRequestHeaderSize: 8KiB
maxResponseHeaderSize: 8KiB
inputBufferSize: 8KiB
idleTimeout: 30 seconds
minBufferPoolSize: 64 bytes
bufferPoolIncrement: 1KiB
maxBufferPoolSize: 64KiB
acceptorThreads: 1
selectorThreads: 2
acceptQueueSize: 1024
reuseAddress: true
useServerHeader: false
useDateHeader: true
useForwardedHeaders: true
adminConnectors:
- type: http
port: 14180
Want to change acceptQueueSize: to 17 instead? It's the same script with just different variable values:
$ awk -v rec='applicationConnectors' -v tag='acceptQueueSize' -v val='17' '
/^ [^ ]/{name=$1} name==(rec":") && $1==(tag":"){sub(/[^ ]+$/,""); $0=$0 val}
1' file
applicationConnectors:
- type: http
port: 14080
bindHost: 15.213.48.154
headerCacheSize: 512 bytes
outputBufferSize: 32KiB
maxRequestHeaderSize: 8KiB
maxResponseHeaderSize: 8KiB
inputBufferSize: 8KiB
idleTimeout: 30 seconds
minBufferPoolSize: 64 bytes
bufferPoolIncrement: 1KiB
maxBufferPoolSize: 64KiB
acceptorThreads: 1
selectorThreads: 2
acceptQueueSize: 17
reuseAddress: true
useServerHeader: false
useDateHeader: true
useForwardedHeaders: true
adminConnectors:
- type: http
port: 14180
Only try that with your currently accepted sed solution if you enjoy counting ns :-). Note also that this will work no matter what order the lines appear within each record since it keys off the name port rather than assuming that will appear some specific number of lines after applicationConnectors:. Finally, this will work even if the strings you're searching for or replacing with contain RE metachars (e.g. .), backreference chars (e.g. \1 or &), or sed delimiters (e.g. /).

Answer 2

Since the port line is the second after applicationConnectors: you need to use double n; and you should use double quotation marks around the sed command to allow variable interpolation inside:
sed "/applicationConnectors:/{n;n;s/\($var2\).*/\1: ${var1}/}" configuration.yml > newfile
See this online sed demo.

Answer 3

staging:
datasource:
jdbcUrl: xxx
driverclassname: yyy
username: zzzz
password: dddd
platform: wwww
sed command to replace value of jdbc url:
sed -i "/staging:/{n;n;s/\(jdbcUrl\).*/\1: AAAAA/}" application.yml