CODEWITHSUNDEEP
bashscriptingpid
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Reputation: 9488

How can a Linux/Unix Bash script get its own PID?

I have a script in Bash called Script.sh that needs to know its own PID. In other words, I need to get PID inside Script.sh.

Any idea how to do this?

Upvotes: 228

Views: 213802

Answers (7)

Pierre13fr
Pierre13fr

Reputation: 311

Wherever you are (on an interactive command line or in a script), and in the case you do NOT have access to $BASHPID, you can get access to your current shell pid with this :

bash -c 'echo $PPID'

where simple quotes are essential to prevent premature string interpretation (so as to be sure the interpretation occurs in the child process, not in the current one). The principle is just to create a child process and ask for its parent pid, that is to say "myself". This code is simpler than ps-based Joakim solution.

Upvotes: 3

Paul Tomblin
Paul Tomblin

Reputation: 182762

The variable $$ contains the PID.

Upvotes: 336

tvanfosson
tvanfosson

Reputation: 532445

use $BASHPID or $$

See the [manual][1] for more information, including differences between the two.

TL;DRTFM

  • $$ Expands to the process ID of the shell.
    • In a () subshell, it expands to the process ID of the invoking shell, not the subshell.
  • $BASHPID Expands to the process ID of the current Bash process (new to bash 4).

Upvotes: 108

Joakim J. Rapp
Joakim J. Rapp

Reputation: 21

If the process is a child process and $BASHPID is not set, it is possible to query the ppid of a created child process of the running process. It might be a bit ugly, but it works. Example:

sleep 1 &
mypid=$(ps -o ppid= -p "$!")

Upvotes: 2

neo
neo

Reputation: 1270

The PID is stored in $$.

Example: kill -9 $$ will kill the shell instance it is called from.

Upvotes: 11

Dennis Williamson
Dennis Williamson

Reputation: 359855

In addition to the example given in the Advanced Bash Scripting Guide referenced by Jefromi, these examples show how pipes create subshells:

$ echo $$ $BASHPID | cat -
11656 31528
$ echo $$ $BASHPID
11656 11656
$ echo $$ | while read line; do echo $line $$ $BASHPID; done
11656 11656 31497
$ while read line; do echo $line $$ $BASHPID; done <<< $$
11656 11656 11656

Upvotes: 46

Klaus Byskov Pedersen
Klaus Byskov Pedersen

Reputation: 120917

You can use the $$ variable.

Upvotes: 8

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