# If you'd like to omit non-matching lines from the result; add ';d' to the end of the expression.
sed -E 's/(([A-Z]+)-([0-9]+))\[([A-Z]+)-([A-Z0-9-]+)(\])/\1 \4/gm;t' <<< "PSHELF-2[PSHELF-MF-6RU]
SHELF-5[SHELF-M6]
SHELF-6[SHELF-M15]
SHELF-6[SHELF-M15]"
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