Ubuntu – Extract word from string using grep/sed/awk

awkbashcommand linegrepsed

I have a string

00:28:04 /usr/lib/jvm/jre/bin/java -DJDBC_CONNECTION_STRING= -Dspring.profiles.active=qa -XX:MaxPermSize=256


and want to extract the word qa that follows -Dspring.profiles.active.

I have the string save in a file text.txt just to demo on it.

When I do

grep -r -o "spring.profiles.active=" text.txt


The result is spring.profiles.active=

This word does not always be qa, it could be prod or dev.

What I'd like to do is find the word spring.profiles.active and after the = extract that word.

I would like to shell script this because I use the word to configure other items on the server.

Is this possible and if so, how do I do it.

You can use grep with PCRE (-P):

grep -Po 'spring.profiles.active=\K[^ ]+' <<<'.....string.....'

• spring.profiles.active= will match this substring literally, \K will discard the match

• [^ ]+ will select the desired portion i.e. the portion after spring.profiles.active=, till the next space

For a file:

grep -Po 'spring.profiles.active=\K[^ ]+' file.txt


Example:

% grep -Po 'spring.profiles.active=\K[^ ]+' <<<'00:28:04 /usr/lib/jvm/jre/bin/java -DJDBC_CONNECTION_STRING= -Dspring.profiles.active=qa -XX:MaxPermSize=256'
qa


sed would take similar logic:

sed -r 's/.*spring.profiles.active=([^ ]+).*/\1/' <<<'.....string.....'


Example:

% sed -r 's/.*spring.profiles.active=([^ ]+).*/\1/' <<<'00:28:04 /usr/lib/jvm/jre/bin/java -DJDBC_CONNECTION_STRING= -Dspring.profiles.active=qa -XX:MaxPermSize=256'
qa


Handling errors:

In your script you may want to handle the case where there is no match, in other words where your original string does not contain spring.profiles.active=. In the above sed example, you obtain the whole original string, which could create problems:

% var="$(sed -r 's/.*spring.profiles.active=([^ ]+).*/\1/' <<<'00:28:04 /usr/lib/jvm/jre/bin/java -DJDBC_CONNECTION_STRING= -XX:MaxPermSize=256')" % echo$var
00:28:04 /usr/lib/jvm/jre/bin/java -DJDBC_CONNECTION_STRING= -XX:MaxPermSize=256


If you prefer to obtain the empty string when there is no match, add the -n option to the sed command and the p option to the sed s command, like this:

% var="$(sed -rn 's/.*spring.profiles.active=([^ ]+).*/\1/p' <<<'00:28:04 /usr/lib/jvm/jre/bin/java -DJDBC_CONNECTION_STRING= -XX:MaxPermSize=256')" % echo$var

% var="$(sed -rn 's/.*spring.profiles.active=([^ ]+).*/\1/p' <<<'00:28:04 /usr/lib/jvm/jre/bin/java -DJDBC_CONNECTION_STRING= -Dspring.profiles.active=qa -XX:MaxPermSize=256')" % echo$var
qa


Then you can test if \$var is empty or not.