CODEWITHSUNDEEP
bashexprparameter-expansion
mrblippy
mrblippy

Reputation: 311

Bash expr command

I am trying to make a bash shell script that can add a name value pair to a text file, for example TEST=true. I am trying to make it so if the user tries to add a name that already exists for example TEST=false it does not let them to do it. Can anyone tell me how to use the expr command to extract any text before the = character? Any help would be greatly appreciated.

thanks

Upvotes: 0

Views: 729

Answers (2)

ghostdog74
ghostdog74

Reputation: 342849

expr is an external command. you can just use bash to do it

s="TEST=true"
echo ${s%%=*}


OLDIFS="$IFS"
IFS="="
set -- $s
echo $1
IFS="$OLDIFS"

Upvotes: 1

tarrasch
tarrasch

Reputation: 2680

is that what you need?

if [[ $input =~ (.?*)= ]]

then 

    echo $BASH_REMATCH is what I wanted    

    echo but just ${BASH_REMATCH[1]}

fi

http://aplawrence.com/Linux/bash-regex.html

Upvotes: 0

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