# If you'd like to omit non-matching lines from the result; add ';d' to the end of the expression.
sed -E 's/^(.*\.)(\d+)\\(\n\1\d+\\)+$/$1$2\\/gm;t' <<< "D:\folder1\folder2\folder3\Artifact\Artifact-1.1\
D:\folder1\folder2\folder3\Artifact\Artifact-1.2\
D:\folder1\folder2\folder3\Artifact\Artifact-1.3\
D:\folder1\folder2\folder3\Different_Artifact\Different_Artifact-17.1\
D:\folder1\folder2\folder3\Different_Artifact\Different_Artifact-17.4\
D:\folder1\folder2\folder3\Different_Content\Different_Content-2.0\
D:\folder1\folder2\folder3\folder4\Different_Content\Different_Content-2.0\
D:\folder1\folder2\folder3\folder4\Different_Content\Different_Content-2.2\"
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for SED, please visit: https://www.gnu.org/software/sed/manual/html_node/The-_0022s_0022-Command.html