Sponsored Content
Top Forums Programming How to find if a process a daemon ? Post 302218737 by Perderabo on Saturday 26th of July 2008 08:15:11 AM
Old 07-26-2008
Quote:
Originally Posted by matrixmadhan
Any process guarded from SIGHUP signal as nohup process and detached from controlling terminal will have a ppid of 1
Not true. Any time any daemon which happens to be ignoring sighup forks, it creates a counterexample to this statement. (init could fork without creating a counterexample, but it never ignores hup)
Quote:
Originally Posted by matrixmadhan
but they are not daemonized.
Actually any process that happens to meet these criteria are daemons. No controlling terminal means the process is a daemon. Whether or not a process is a daemon has nothing to do with the ppid or what signals it is ignoring.

With most versions of unix when you log in on the system console, the ppid of your login shell will be 1. Before the rise of tcp/ip the ppid of every login shell was 1. None of these login shells are daemons, they all have controlling terminals. You still may have other getty lines in /etc/inittab. Each such line is a potential interactive shell with a ppid of 1. But most other children spawned by init do not open ttys and remain daemons.

When a process exits, its children become owned by init. This does not impact whether of not those children are daemons. Some are. Some aren't.

cron will not have a pid of 1. Every time cron spawns a process, that new process is a daemon. Each of these daemons will not have a ppid of 1... their ppid will be pointing to cron.

When you need to determine if a process is a daemon or not, the ppid is completely irrelevant. Daemons and non-daemons can have a ppid of 1. Daemons and non-daemons can have a ppid other than one.

Daemons sometimes choose to not ignore sighup. Both inetd and init itself are examples of daemons that are listening for a HUP. When they get one, they reconfigure themselves. But it is more common for a daemon to be ignoring HUP.

It really it very simple.
Daemons have no controlling terminal.
Non-daemons have a controlling terminal.

Examples of stuff that have no bearing on a process' daemon status...
pid
ppid
signal mask
 

10 More Discussions You Might Find Interesting

1. Programming

Daemon process

Hi, I have to write a daemon process, which performs certain operations in the background. Now since it performs operations in the background, it should not display anything to the standard output. The problem is that it still displays, text on standard output. Can anyone tell me (it is... (2 Replies)
Discussion started by: s_chordia
2 Replies

2. Programming

What is a daemon process?

This is gonna seem really silly to almost evryone here - but I need to know : what is a daemon process? Thanks (6 Replies)
Discussion started by: Kanu77
6 Replies

3. UNIX for Advanced & Expert Users

zombie daemon process!!

My daemon process is the child of init and init has the responsibility to remove it, once it turns zombie. But I want to ask why the daemon process which is child of init turns zombie in the first place. What measures I have to take to avoid this? rish (1 Reply)
Discussion started by: rish2005
1 Replies

4. Linux

daemon process

how i will write the daemon process,if any body have sample daemon process send me. (1 Reply)
Discussion started by: suresh_rupineni
1 Replies

5. Shell Programming and Scripting

How to starting process as daemon using ssh command?

Hello, I need to run a command on remote Linux using the ssh command from my local machine. I am able to execute the command on remote machine using ssh but it's behaving strangely. The command is supposed to start a daemon process on remote linux box and the control should return back to me... (5 Replies)
Discussion started by: nitinshukla
5 Replies

6. UNIX for Dummies Questions & Answers

How to write Pro*C daemon process using multithreading?

Hello, I am new to this forum and this is my first post here... I have never worked on either Pro*C or Multithreading..Now, i have to write a Pro*C, Multithreading daemon process.. I dont know where to start.. Can anybody help me with examples? 1. need to write a Pro*C multithreading... (0 Replies)
Discussion started by: kachiraju
0 Replies

7. Shell Programming and Scripting

Diff between Bg and daemon process

Dear Unix Gurus, Plz provide major diff between background process and daemon process. Is it control available for daemon process?. (3 Replies)
Discussion started by: kkl
3 Replies

8. Shell Programming and Scripting

run this script as a daemon process

Hi, HI , I have a simple script that moves files from one folder to another folder, I have already done the open-ssh server settings and the script is working fine and is able to transfer the files from one folder to another but right now I myself execute this script by using my creditianls to... (3 Replies)
Discussion started by: nks342
3 Replies

9. UNIX for Dummies Questions & Answers

Oracle process running as user daemon

Hi, When process listing, I came across a process running as user daemon. daemon 23576 23574 0 07:32:04 ? 0:07 oracle (DESCRIPTION=(LOCAL=YES)(ADDRESS=(PROTOCOL=beq))) root 27526 27444 1 07:38:43 ttyp5 0:00 grep 23574 why a process runs as user daemon, when it should be... (3 Replies)
Discussion started by: wilsonee
3 Replies

10. Programming

Daemon process

I wish to make a process run in the background, but only one instance of it, and not many, so when the program is loaded, it has to check whether another instance of the same program is running and if so to exit. How do I do this ? (4 Replies)
Discussion started by: sundaresh
4 Replies
PKILL(1)						    BSD General Commands Manual 						  PKILL(1)

NAME
pkill -- find or signal processes by name SYNOPSIS
pgrep [-filnvx] [-d delim] [-G gid] [-g pgrp] [-P ppid] [-s sid] [-t tty] [-U uid] [-u euid] pattern ... pkill [-signal] [-filnvx] [-G gid] [-g pgrp] [-P ppid] [-s sid] [-t tty] [-U uid] [-u euid] pattern ... prenice [-l] priority pattern ... DESCRIPTION
The pgrep command searches the process table on the running system and prints the process IDs of all processes that match the criteria given on the command line. The pkill command searches the process table on the running system and signals all processes that match the criteria given on the command line. The prenice command searches the process table on the running system and sets the priority of all processes that match the criteria given on the command line. The following options are available for pkill and pgrep: -d delim Specify a delimiter to be printed between each process ID. The default is a newline. This option can only be used with the pgrep command. -f Match against full argument lists. The default is to match against process names. -G gid Restrict matches to processes with a real group ID in the comma-separated list gid. -g pgrp Restrict matches to processes with a process group ID in the comma-separated list pgrp. The value zero is taken to mean the process group ID of the running pgrep or pkill command. -i Ignore case distinctions in both the process table and the supplied pattern. -l Long output. Print the process name in addition to the process ID for each matching process. If used in conjunction with -f, print the process ID and the full argument list for each matching process. -n Match only the most recently created process, if any. -P ppid Restrict matches to processes with a parent process ID in the comma-separated list ppid. -s sid Restrict matches to processes with a session ID in the comma-separated list sid. The value zero is taken to mean the session ID of the running pgrep or pkill command. -t tty Restrict matches to processes associated with a terminal in the comma-separated list tty. Terminal names may be specified as a fully qualified path, in the form 'ttyXX', or 'pts/N', (where XX is any pair of letters, and N is a number), or the shortened forms 'XX' or 'N'. A single dash ('-') matches processes not associated with a terminal. -U uid Restrict matches to processes with a real user ID in the comma-separated list uid. -u euid Restrict matches to processes with an effective user ID in the comma-separated list euid. -v Reverse the sense of the matching; display processes that do not match the given criteria. -x Require an exact match of the process name, or argument list if -f is given. The default is to match any substring. -signal A non-negative decimal number or symbolic signal name specifying the signal to be sent instead of the default TERM. This option is valid only when given as the first argument to pkill. The -l flag is also availale for prenice. Note that a running pgrep or pkill process will never consider itself or system processes (kernel threads) as a potential match. EXIT STATUS
pgrep, pkill, and prenice return one of the following values upon exit: 0 One or more processes were matched. 1 No processes were matched. 2 Invalid options were specified on the command line. 3 An internal error occurred. SEE ALSO
grep(1), kill(1), ps(1), kill(2), sigaction(2), re_format(7), signal(7), renice(8) HISTORY
pkill and pgrep first appeared in NetBSD 1.6. They are modelled after utilities of the same name that appeared in Sun Solaris 7. prenice was introduced in NetBSD 6.0. BSD
December 7, 2010 BSD
All times are GMT -4. The time now is 06:06 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy