How to get just numerical value from a string in bash

Question

I have an xml file and i want to extract just the numerical value from a string in the file.One of the solution i came up with is

cat file.xml |grep -i "mu "| grep -o '[0-9]'

But i get each digit separated by new line,e.g for 100,i get 1 then new line,then 0 and so on.The other solution i came up with is

cat file.xml |grep -i "mu "|cut -d ' ' -f 4| tr '=' ' '|cut -d ' ' -f2|tr '""' ' '|sed -e 's/^ *//g' -e 's/ *$//g'

My question: Is there a simpler solution to this problem that i get just a numerical value from a line without caring about fields and not to use cut or tr commands?

<mu value="100" /> But it can be different e.g there can be space between value and = sign. — rizvaughan
– rizvaughan, Commented Nov 22, 2013 at 17:08

anubhava · Accepted Answer · 2013-11-22 17:07:38Z

4

Use this egrep:

egrep -o '[0-9]+'

answered Nov 22, 2013 at 17:07

anubhava

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tripleee Over a year ago

Or in context grep -i "mu" file.xml | grep -Eo '[0-9]+'

iruvar · Accepted Answer · 2013-11-22 17:10:59Z

0

One option you have is to delete everything that is not a digit from your input

tr -cd '[:digit:]'

Or for floating numbers

tr -cd '[:digit:].'

answered Nov 22, 2013 at 17:10

iruvar

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rizvaughan Over a year ago

Thank you,it worked for me but not very comfortable with [:digit:]

petrus4 · Accepted Answer · 2013-11-22 18:03:16Z

I would encourage avoidance of XML as a format, personally; at least for your own use. Instead of "<mu value="100" />", you could use the following:-

# Name your data file ma-me-mo-mu.txt 100+200+300+400

and then:-

while IFS='+' read ma me mo mu do echo "${ma}" echo "${me}" echo "${mo}" echo "${mu}" done

You don't need to name your columns inside the data file itself. They go in the file name.

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