54

If I'm assigning a variable with

temp=$!

what would it be its value?

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76

$! contains the process ID of the most recently executed background pipeline. From man bash:

Special Parameters

The shell treats several parameters specially. These parameters may only be referenced; assignment to them is not allowed.

...

! - Expands to the process ID of the most recently executed background (asynchronous) command.

For example:

$ sleep 60 &
[1] 6238
$ echo "$!"
6238
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1
  • I get the feeling that you and slm are saying about the same thing :) – msw Jul 31 '13 at 10:56
28

From Bash's man page:

   !   Expands to the process ID of the most recently executed 
       background (asynchronous) command.

So $! would contain the process ID (PID) of the last job that was backgrounded.

Example

$ sleep 100 &
[1] 18813

$ echo "$!"
18813

References

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4
  • 1
    I get the feeling that you and Chris Down are saying about the same thing :) – user Jul 31 '13 at 9:25
  • 2
    It would seem there's an echo on this Question 8-). – slm♦ Jul 31 '13 at 11:30
  • Same votes counts, too! – user Jul 31 '13 at 12:03
  • @MichaelKjörling - hey great minds think alike 8-). – slm♦ Jul 31 '13 at 12:09

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