Pass variable from command line to mongo command

Question

I have a script which does:

mongo localhost:27017/MyDB --eval "db = connect("localhost:27017/SomeDB")"
mongo localhost:27017/MyDB --eval "db.copyDatabase(var1frombatch, var2frombatch)"
PAUSE

in which var1frombatch & var2frombatch are passed to this batch from c#.net code as %1, %2, my question is how can i use the variable in my --eval doe ?

I tried

mongo localhost:27017/MyDB --eval "db = connect("localhost:27017/SomeDB")"
mongo localhost:27017/MyDB --eval "db.copyDatabase('%1', '%2')"
PAUSE

but did not work

What does the parser execute? (run it with echo on to see) — Stephan
– Stephan, Commented May 27, 2016 at 6:27
so your question isn't "how can I use the variable in the batchfile" but "how do I pass a variable to the batchfile". Sadly I can't help you with c#. — Stephan
– Stephan, Commented May 27, 2016 at 6:58
Thanks for the reply man, but that's not what i mean, i already have the variable passed into this batch script of mine. They are %1 and %2, now i want to use them in the --eval section as database names, but i cannot parse them — user1452954
– user1452954, Commented May 27, 2016 at 7:10

Kevin · Accepted Answer · 2016-05-27 08:22:05Z

1

MongoDB has an feature to run shell scripts on the command line. In your case, one javascript for multiple operations works better than evaluate multiple mongodb functions.

Run a script like:

%MONGODBDIR%mongo localhost:27017/SMSManagement --eval "var dbA = '%1', dbB = '%2'" %SCRIPTSDIR%\shellscript.js

And in your shellscript.js

print("Copying database from " + "database:" + dbA + " to " + "database:" + dbB);

var result = db.copyDatabase(dbA, dbB)
printjson(result);

The result will output like:

{ "ok" : 1 }

More information about this you can read here: https://docs.mongodb.com/manual/tutorial/write-scripts-for-the-mongo-shell/

answered May 27, 2016 at 8:22

Kevin

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3 Comments

user1452954 Over a year ago

hello thanks for your reply, your code did not work, the program cannot recognize %1 and %2 inside --eval

Kevin Over a year ago

You told that %1 and %2 are the arguments? Place the script in a bat file and call batch.bat "DB_A" "DB_B"' and %1 and %2 should works like it supposed to.

user1452954 Over a year ago

Yeah, i tied and its working now, thanks a lot man, it was very helpful !

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