Use Bash variable with Sed command

bash

Problem Description

I'm expecting to replace all instances of ${version.number} with the contents of the variable "version". Instead the literal text $version is being inserted.

What do I need to do to make sed use the current value of $version instead?

#!/bin/bash
version=$1
echo $version
sed 's/\${version.number}/$version/' template.txt > readme.txt

Solution

sed "s/\${version.number}/$version/" template.txt > readme.txt

Only double quotes do dollar-sign replacement. That also means single quotes don't require the dollar sign to be escaped.

Get 10-th line from file

sed "10q;d" file.txt

argument q: quit searching
argument d: delete pattern space, start next cycle

To store the output to a variable, use

line=$(sed "10q;d" file.txt)
echo $line

Source

http://stackoverflow.com/questions/3204302/how-to-use-a-bash-script-variable-with-sed

http://stackoverflow.com/questions/6022384/bash-tool-to-get-nth-line-from-a-file

http://stackoverflow.com/questions/6749128/store-output-from-sed-into-a-variable