How to increment a numerical value in properties file - bash

Question

I have a version.properties file as below:
#some comments
major=2
minor=16
patch=4
I want to increase the minor value by 1. so new value should be 16 +1 = 17.
So the updated file will be:
#some comments
major=2
minor=17
patch=4
Is it possible to achieve this through bash script?
Thanks in advance

Answer 1

You could use awk:
awk -F"=" 'BEGIN{OFS=FS} $1=="minor"{$2=$2+1}1' versions.properties
This awk script says:
Split each record by a an equal sign (-F"=")
Ensure that the output field separator OFS is equal to the incoming field separator FS (BEGIN{OFS=FS})
If the first field is the word "minor" ($1=="minor")
Then add 1 to the second field ({$2=$2+1})
Finally print the record back out 1.
You can redirect this to a temp file and then mv the temp back over the top of the original:
awk -F"=" 'BEGIN{OFS=FS} $1=="minor"{$2=$2+1}1' versions.properties > versions.properties.tmp && mv versions.properties.tmp versions.properties

Answer 2

You can also use this:
#! /bin/bash
LINE=$(cat version.properties | grep minor)
VAL=$(echo $LINE | cut -f 2 -d "=")
VAL=$(($VAL + 1))
NEW_LINE=$(echo minor=$VAL)
sed -e "s,$LINE,$NEW_LINE,g" -i version.properties
It fixes the issue without the need to use additional redirections and mv commands. Hope this helps :-)

Answer 3

Steps:
1- Get line number of your parameter (to use in replacement)
grep -n "minor" version.properties | cut -d: -f1
This shows "3" according to your version.properties file
We save it in a variable
line=$(grep -n "minor" version.properties | cut -d: -f1)
2- Get key=value
grep -n "minor" version.properties | cut -d: -f2
This shows minor=16 according to your version.properties file
We save it in a variable called string:
string=$(grep -n "minor" version.properties | cut -d: -f2)
3- Get version of this string : minor=16
version=$(echo $string | cut -d= -f2)
4- Increase version
newVersion=$(( version + 1))
5- Replace in original properties file using line number:
sed -i "$line c $key=$newVersion" version.properties
Finally this is a complete script , with key and file as parameters, so you could use it to increase any key like in any properties file, in any location :
key=$1
file=$2
line=$(grep -n "$key" $file | cut -d: -f1)
string=$(grep -n "$key" $file | cut -d: -f2)
# get version from string
version=$(echo $string | cut -d= -f2)
#increase version
newVersion=$(( version + 1))
#update file
sed -i "$line c $key=$newVersion" $file
Usage:
bash update_version.sh "patch" /server/files/version.properties
Note : keys in file must be unique.