CODEWITHSUNDEEP
linuxbashscriptingsedreplace
AlbertEngelB
AlbertEngelB

Reputation: 16436

Getting sed to Replace Text With Argument

Alright, I know this is a simple question, but I can't seem to get this sed command to work. I'm trying to get a text file and replace one bit of it from placeholder text to a study code. The study code that it is going to replace it with is passed into the script using arguments when the script is first ran. The problem is, when I try to replace the placeholder text with the variable $study, it replaces it with a literally "$study".

Right now my arguments set like this:

export study=$1

export tag=$2

export mode=$3

export select=$4

My sed command looks like this:

sed -i.backup -e 's/thisisthestudycodereplacethiswiththestudycode/$study/' freq.spx

Is there some easy way of getting sed to not look at the literal $study, or would it be better at this point to do it another way?

Upvotes: 4

Views: 7328

Answers (3)

amar
amar

Reputation: 499

try this................... sed -e 's/%d/'$a'/g' amar.htm , amar.htm having the string "%d" which is indeed to be replaced and "a" is having the string to replace.

Upvotes: 0

ephemient
ephemient

Reputation: 204678

You probably won't run into this issue, but just in case...

Paul's answer is slightly suboptimal if $study might contain slashes or other characters with special meaning to sed.

mv freq.spx freq.spx.backup && \
    awk -v "study=$study" '{
        gsub(/thisisthestudycodereplacethiswiththestudycode/, study);
        print;
    }' freq.spx.backup > freq.spx

Although awkward (hah, pun!), this will always work regardless of $study's contents.

Upvotes: 1

Paul Tomblin
Paul Tomblin

Reputation: 182772

Use double quotes instead of single quotes.

Because ' quoting prevents shell variable expansions, and " quoting does not.

Upvotes: 17

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