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rated 0 times [  1074] [ 0]  / answers: 3 / hits: 479518  / 2 Years ago, thu, october 20, 2022, 1:44:12

In tutorials and how-to's I often see commands combined. For instance,

sudo apt-get update && sudo apt-get install pyrenamer

There seem to be four possible connectors: &, &&, || and ;. Though the & connector is clear to me (it sends a process to the background and leaves the terminal available), it is not clear what the difference is between && and ;. And I did not know of || until Kaya's comment.

The following questions deal with the difference between the two connectors, but do so mostly in the comments:

So here are a number of related questions:

  1. What is the difference between ; and &&?

  2. When should you use them respectively? It would be nice to see some use cases: if I want to run a command and then after it shutdown my computer, which connector should I choose?

  3. What are their advantages and dangers? Robie Basak mentions in a comment to this answer that a command like cd /somewhere_else; rm -Rf * can have destructive consequences if the first element in the command chain fails, for instance.

  4. If relevant, where do they come from?

More From » command-line



A; B    # Run A and then B, regardless of success of A
A && B # Run B if and only if A succeeded
A || B # Run B if and only if A failed
A & # Run A in background.

[#29866] Friday, October 21, 2022, 2 Years  [reply] [flag answer]
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