What is $! ?

guruparan18 · #1 (**permalink**) 2 Weeks Ago

Hi All,

What is the meaning for $! in shell? I am trying to understand a script. And it has the following sequence of commands.

Code:

local@usr> a=1
local@usr> echo $a
1
local@usr> echo $!a
a

It is printing the variable back. Is it all for that? What are the other $x option you have? Few I know are $$, $*, $?. If anyone can point me to a good source, it will be helpful.

scottn · #2 (**permalink**) 2 Weeks Ago

$! is a special shell variable which gives the process ID of the last background job you ran.

What does this give you:

Code:


local@usr> a=1
local@usr> echo $a
1
local@usr> sleep 1 &
local@usr> echo $!a

Bits Awarded / Charged to scottn for this Post
Date	User	Comment	Amount
2 Weeks Ago	guruparan18	Good one. Thanks	1,000

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Display Modes	Rate This Thread
Switch to Linear Mode Hybrid Mode Switch to Threaded Mode	Rate This Thread:


	Powered by