What does this "subst" invocation do?

Question

I would like to know what this command does in a batch script:

subst Q: /D  1>nul  2>nul

Create a file nul with contents: Invalid parameter - Q: – David Harris Jul 25 '12 at 23:13 — David Harris, Jul 25 '12 at 23:13

Keith Flower · Answer 1 · 2012-07-25T23:25:35.527

1

That looks like a DOS command (not bash).

subst substitutes a folder for a drive letter or substitutes one drive letter for another

The /D deletes (actually unmounts) a virtual (previously substituted) drive. So your command basically removes the virtual drive Q:

The 1>nul and 2>nul just get rid of the output (ie sends the standard output and standard error output to the nul device).

edited Jul 25 '12 at 23:25

answered Jul 25 '12 at 23:14

Keith Flower

And there's no bash equivalent to this command, as UNIX doesn't have drive letters. – Jul 25 '12 at 23:49
Yep. Gave me some traumatic flashbacks there for a moment, too. My edit to his/her tags and title is queued for review. – Keith Flower Jul 25 '12 at 23:52

score 0 · Answer 2 · answered Jul 25 '12 at 23:16

0

The subst command you are talking about is a DOS command, not bash.

What it does, is that it unmounts the virtual drive Q:, and the 1 > nul 2 > nul basically means that all output from the command is discarded.

answered Jul 25 '12 at 23:16

Wouter

2 Answers2