CODEWITHSUNDEEP
regexlinuxbash
dukeofgaming
dukeofgaming

Reputation: 3198

How to extract multiple environment variables from a regular expression in Bash?

I essentially want to extract the parts from a URL into different environment variables for use later, so I am expecting to be able to do something like this:

echo "my-app.domain.com:8080" | \
sed -r 's/((\w+)\.)?(\w+\.\w+)(\:(\d+))?/\2\n\3\n\5/g' | \
read SUBDOMAIN DOMAIN PORT

However this does not seem to work (and for some reason the ":" from the port is always output in "\5"):

sh-4.2# echo "my-app.domain.com:8080" | \
sed -r 's/((\w+)\.)?(\w+\.\w+)(\:(\d+))?/\2\n\3\n\5/g'
my-app
domain.com
:8080

What is more strange to me is that if I print a new line after the \5, this will be the output:

sh-4.2# echo "my-app.domain.com:8080" | sed -r 's/((\w+)\.)?(\w+\.\w+)(\:(\d+))?/\2\n\3\n\5\n/g'
my-app
domain.com

:8080

In any case, when using read, none of the variables are set either... seems I am doing a number of things wrong but am unable to spot exactly what.

Upvotes: 0

Views: 1216

Answers (2)

Cyrus
Cyrus

Reputation: 88731

With GNU bash:

url="my-app.domain.com:8080"
[[ $url =~ ([^.]*)\.(.*):(.*) ]] 
subdomain="${BASH_REMATCH[1]}"
domain="${BASH_REMATCH[2]}"
port="${BASH_REMATCH[3]}"
echo "$subdomain $domain $port"

Output:

my-app domain.com 8080

See: The Stack Overflow Regular Expressions FAQ

Upvotes: 3

Hans-Martin Mosner
Hans-Martin Mosner

Reputation: 846

This is a duplicate, see Bash script, read values from stdin pipe In particular, the bash built-in "shopt -s lastpipe" will cause the "read" command to be executed within this shell instead of a subshell.

Upvotes: -1

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