MongoDB script to check the status of background index builds

Here is a simple script I’ve found to be quite helpful for monitoring the status of background index builds across shards on a system:

var currentOps = db.currentOp();

if(!currentOps.inprog || currentOps.inprog.length < 1) {
    print("No operations in progress");
} else {
    for(o in currentOps.inprog) {
        var op = currentOps.inprog[o];
        if(op.msg && op.msg.match(/bg index build/)) {
            print(op.opid+' - '+op.msg);
        }
    }
}

Here's the output:

$ mongo mycluster:30000/mydb bgIndexBuildStatus.js 
MongoDB shell version: 1.8.1
connecting to: mycluster:30000/mydb
shard0000:343812263 - bg index build 122042652/165365928 73%
shard0001:355224633 - bg index build 111732254/165568168 67%