Use extended regexp for better readability

Author: bgandon

check

@@ -31,10 +31,10 @@ latest_version=$(
     (
         curl --silent --fail --show-error --location \
                 --url "https://artfiles.org/openssl.org/source/old/${directory}/" \
-            | sed -ne 's/^.*href="openssl-\([0-9.]\{1,\}[a-z]\{0,2\}\)\.tar\.gz">.*/\1/p'
+            | sed -nEe 's/^.*href="openssl-([0-9.]+[a-z]{0,2})\.tar\.gz">.*/\1/p'
         curl --silent --fail --show-error --location \
                 --url "https://artfiles.org/openssl.org/source/" \
-            | sed -ne 's/^.*href="openssl-\([0-9.]\{1,\}[a-z]\{0,2\}\)\.tar\.gz">.*/\1/p'
+            | sed -nEe 's/^.*href="openssl-([0-9.]+[a-z]{0,2})\.tar\.gz">.*/\1/p'
     ) \
         | grep --color="never" -F "${source_family}" \
         | sort --version-sort \

in

@@ -36,10 +36,10 @@ tarball_url=$(
     (
         curl --silent --fail --show-error --location \
                 --url "https://artfiles.org/openssl.org/source/old/${directory}/" \
-            | sed -ne 's|^.*href="\(openssl-'"${version}"'\.tar\.gz\)">.*|https://www.openssl.org/source/old/'"${directory}"'/\1|p'
+            | sed -nEe 's|^.*href="(openssl-'"${version}"'\.tar\.gz)">.*|https://www.openssl.org/source/old/'"${directory}"'/\1|p'
         curl --silent --fail --show-error --location \
                 --url "https://artfiles.org/openssl.org/source/" \
-            | sed -ne 's|^.*href="\(openssl-'"${version}"'\.tar\.gz\)">.*|https://www.openssl.org/source/\1|p'
+            | sed -nEe 's|^.*href="(openssl-'"${version}"'\.tar\.gz)">.*|https://www.openssl.org/source/\1|p'
     ) | tail --lines="1"
 )
 if [[ -z ${tarball_url} ]]; then