# If you'd like to omit non-matching lines from the result; add ';d' to the end of the expression.
sed -E 's/"amount":"[\$]?([0-9]{1,3}),([0-9]{1,3})"/"amount":"$1$2",/gm;t' <<< "[{\"team\":\"Green Bay Packers\",\"active\":\"1\",\"year_started\":\"2018\",\"end_year\":\"2022\",\"amount\":\"$2,578,408\",\"amount_guaranteed\":\"$118,408\"}]
[{\"team\":\"San Diego Padres\",\"active\":\"0\",\"year_started\":\"2020\",\"end_year\":\"2020\",\"amount\":\"563,500\",\"amount_guaranteed\":\"\"},{\"team\":\"San Diego Padres\",\"active\":\"0\",\"year_started\":\"2019\",\"end_year\":\"2019\",\"amount\":\"555,000\",\"amount_guaranteed\":\"\"}]
[{\"team\":\"Washington Wizards\",\"active\":\"1\",\"year_started\":\"2019\",\"end_year\":\"2021\",\"amount\":\"$12,000,000\",\"amount_guaranteed\":\"$12,000,000\"},{\"team\":\"Orlando Magic\",\"active\":\"0\",\"year_started\":\"2011\",\"end_year\":\"2011\",\"amount\":\"522,472\",\"amount_guaranteed\":\"\"},{\"team\":\"Orlando Magic\",\"active\":\"0\",\"year_started\":\"2012\",\"end_year\":\"2013\",\"amount\":\"2,854,389\",\"amount_guaranteed\":\"\"},{\"team\":\"Oklahoma City Thunder\",\"active\":\"0\",\"year_started\":\"2014\",\"end_year\":\"2014\",\"amount\":\"923,373\",\"amount_guaranteed\":\"\"},{\"team\":\"Houston Rockets\",\"active\":\"0\",\"year_started\":\"2014\",\"end_year\":\"2014\",\"amount\":\"981,084\",\"amount_guaranteed\":\"\"},{\"team\":\"Washington Wizards\",\"active\":\"0\",\"year_started\":\"2015\",\"end_year\":\"2015\",\"amount\":\"1,100,602\",\"amount_guaranteed\":\"\"},{\"team\":\"Detroit Pistons\",\"active\":\"0\",\"year_started\":\"2016\",\"end_year\":\"2018\",\"amount\":\"18,000,000\",\"amount_guaranteed\":\"\"}]"
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