const regex = /^(.+)\/(.+)(.cue)$/gm;
// Alternative syntax using RegExp constructor
// const regex = new RegExp('^(.+)\\\/(.+)(.cue)$', 'gm')
const str = `Bryan Adams - 1988 Live! Live! Live!/Bryan Adams - Live! Live! Live!.cue
Bryan Adams - 1993 So Far So Good/Bryan Adams - So Far So Good.cue
Bryan Adams - 2005 Anthology/CD2/Bryan Adams - Anthology CD2.cue
Bryan Adams - 2005 Anthology/CD1/Bryan Adams - Anthology CD1.cue
Bryan Adams - 1988 Hits On Fire/Bryan Adams - Hits On Fire.cue
Bryan Adams - 1997 MTV Unplugged/Bryan Adams - MTV Unplugged.cue`;
const subst = `pushd '$1'\nshnsplit -t %n-%t -o flac -f '$2$3' '$2.flac' && rm -f '$2.flac'\npopd\n`;
// The substituted value will be contained in the result variable
const result = str.replace(regex, subst);
console.log('Substitution result: ', result);
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 JavaScript, please visit: https://developer.mozilla.org/en/docs/Web/JavaScript/Guide/Regular_Expressions