What does "$$" means in shell script?

Question

I came across "$$" expression in shell script, something like this

TFILE=$$

Can anyone tell me its meaning?

score 24 · Accepted Answer · answered Dec 09 '09 at 22:15

24

$$ means the process ID of the currently-running process.

answered Dec 09 '09 at 22:15

Ether

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Thank you, now the code is making sense !!! – Vinit Dhatrak Dec 09 '09 at 22:36

score 5 · Answer 2 · edited May 23 '17 at 12:13

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It's the process id of the current process - see a previous question on StackOverflow for details: What does $$ mean in the shell?

edited May 23 '17 at 12:13

Community

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answered Dec 09 '09 at 22:17

teapot7

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score 1 · Answer 3 · answered Dec 11 '09 at 12:34

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$$ is the process id of the currently running process in UNIX.

mostly it is used with naming of logfiles aor temp files, such that there is no conflict of file names while multiple instances of the same scripts are running.

answered Dec 11 '09 at 12:34

Venkataramesh Kommoju

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score 0 · Answer 4 · answered Feb 06 '11 at 11:19

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echo "$$" prints PID of current running process.

answered Feb 06 '11 at 11:19

Ashitosh

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What does "$$" means in shell script?

4 Answers4