# If you'd like to omit non-matching lines from the result; add ';d' to the end of the expression.
sed -E 's/.*LiveId_(\w+).*/This the LiveId string: \1/;t' <<< "Word\\User MRU\\LiveId_7A5166EB69B271A475B25410BA565F1A63A6FD1BD8CF0F780A344EC2B287CCC1\\Plac‌​‌​e MRU"
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