How do I get value of variable from file using shell script?

Question

There is a file post_check.ini I need the value set for:

Max_value=2

How would I get the value 2 from Max_value?

Solution 1

try

grep -Po '(?<=Max_value=).*' post_check.ini

Solution 2

Max_value=$(sed -n '/^Max_value=\([0-9]*\)$/s//\1/p' post_check.ini)

Solution 3

I recommend using crudini which is a dedicated tool to manipulate ini files from shell

value=$(crudini --get /usr/post_check.ini section Max_value)

Details on usage and download at: http://www.pixelbeat.org/programs/crudini/

Comments

[tripleee]

Possible duplicate of bash get string after character

[JumpOffBox]

This one works with one change of, I added the awk '{print $1}' to get first part else it would return whole line. But what if I want to set back the value I got value=$(grep -Po '(?<=Max_value=).*' /usr/post_check.ini|awk '{print $1}') sed -i -r 's/Max_value=[0-9]+/Max_value=0/g' /usr/master.ini echo "$value" sed -i -r 's/Max_value=[0-9]+/Max_value=$value/g' /usr/master.ini value=$(grep -Po '(?<=Max_value=).*' /usr/master.ini|awk '{print $1}') echo "$value" If I reset it to zero and try to set it back to old value How would I do that ?

[Kent]

@JumpOffBox grep can only extract data. cannot set data. you may need awk/sed to do that. But that would be another new question. You could open a new question. Please don't write big block code in comment, it is hard to read.

[tripleee]

Points for the use of an empty pattern after s but maybe simply 's/^Max_value=//p' would be easier to type and comprehend.