How can I supply a password to a console application?

Question

As I come across issues when testing my current application, I often have to tweak the database the app uses. After losing important changes several times, I wrote a program that will back up my database to a file and then check the file into SubVersion. I have found that that backup application is not good enough.

The database is a PostgreSQL database, and my backup application invokes pg_dump to create the backup file. pg_dump is executed in a console window. When the database was on my own machine, it worked well. But when I moved the database to our test server, pg_dump asked for a password. While it's not that big a deal, I'd like to be able to supply the password automatically, since it is available in the backup application.

I've tried to follow advice I've found here, but pg_dump still stops and asks for a password. Here's the code that I thought should have supplied the password:

Process backupProcess = new Process();
backupProcess.StartInfo.UseShellExecute = false;
backupProcess.StartInfo.RedirectStandardInput = true;
backupProcess.StartInfo.FileName = dumpPath + "pg_dump.exe";
backupProcess.StartInfo.Arguments = " --host " + host + 
                                    " --port " + port + 
                                    " --username " + userName + 
                                    " --format custom --blobs --verbose --file " +
                                    "\"" + txtBackupFile.Text + "\" " + dbName;
backupProcess.StartInfo.WindowStyle = ProcessWindowStyle.Normal;
backupProcess.Start();
StreamWriter standardInput = backupProcess.StandardInput;
standardInput.WriteLine("mypassword");
backupProcess.WaitForExit();// Waits here for the process to exit.

Thank you for your help.

RobR

Should really cconsider using Path.Combine(dumpPath, "pg_dump.exe") instead of "dumpPath + "pg_dump.exe". — Andrew Flanagan, Jan 30 '14 at 19:43
Thanks. I didn't realize that method existed. That's a lot nicer than worrying about whether I have the slash or not. — ROBERT RICHARDSON, Jan 30 '14 at 19:48

Pavenhimself · Answer 1 · 2015-07-03T07:24:50.823

4

I have solved this by using

backupProcess.EnvironmentVariables["PGPASSWORD"] = "password";

This way, I avoid the password will be stored on the computer

edited Jul 03 '15 at 07:24

answered Jul 02 '15 at 11:08

Pavenhimself

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backupProcess.StartInfo.EnvironmentVariables["PGPASSWORD"] – Saad Farooq Jul 14 '18 at 13:38

score 1 · Accepted Answer · edited May 23 '17 at 12:22

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Maybe it's cheating a little bit (in the sense that it doesn't really help you answer the question of how to feed input to pg_dump), but you could refer to this answer which suggests the use of a .pgpass file. It would certainly be possible to write to this file dynamically rather than try to interact with the program once it prompts.

Info on .pgpass here.

edited May 23 '17 at 12:22

Community

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answered Jan 30 '14 at 19:40

Andrew Flanagan

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Many thanks for that link. I'll see about setting up a .pgpass file, or I might use the Python script that answer also suggests. I haven't tried either one yet, but while I'm here I'll mark this as an accpeted answer. – ROBERT RICHARDSON Jan 30 '14 at 19:53
It sounds as if automating interaction on the command line (like you might do using the "expect" tool or something similar) in .NET is a little unreliable. By the way, the above program works for me if you write a dummy "pg_dump.exe" that's a .NET program. – Andrew Flanagan Jan 30 '14 at 19:56

How can I supply a password to a console application?

2 Answers2