Pattern to get string between two specific words/characters using grep [duplicate]

Question

I need to extract email address from a string like this (I'm making a log parser): <some text> [email protected], <some text>

with egrep (or grep -Eo). So the string needs to be pulled out only between "from=" and "," , because the other parts of log contain email addresses too, like to= and etc

Answer 1

Using grep -oP:

s='<some text> [email protected], <some text>'
grep -oP '(?<=from=).*?(?=,)' <<< "$s"
[email protected]

OR else avoid lookbehind by using \K:

grep -oP 'from=\K.*?(?=,)' <<< "$s"
[email protected]

In case your grep doesn't support -P (PCRE) use this sed:

sed 's/.*from=\(.*\),.*/\1/' <<< "$s"
[email protected]

Answer 2

Try awk

echo '<text> [email protected], <text>' | awk -F[=,] '{print $2}'

Here $2 can be a different number based on its position.

Sample for word between symbols "(", ")":

echo "Linux Foundation Certified Engineer (LFCE-JP)" | awk -F[\(\)] '{print $2}'
LFCE-JP