# If you'd like to omit non-matching lines from the result; add ';d' to the end of the expression.
sed -E 's/\d(m)"/000/gm;t' <<< "{
\"test1\": [\"300m\",\"50m\",\"0\",\"4\",\"1050m\"],
\"test2\": [\"600m\",\"400m\",\"10m\",\"0\",\"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