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
PGREP(1)							Linux User's Manual							  PGREP(1)

NAME
pgrep, pkill - look up or signal processes based on name and other attributes SYNOPSIS
pgrep [-cflvx] [-d delimiter] [-n|-o] [-P ppid,...] [-g pgrp,...] [-s sid,...] [-u euid,...] [-U uid,...] [-G gid,...] [-t term,...] [pattern] pkill [-signal] [-fvx] [-n|-o] [-P ppid,...] [-g pgrp,...] [-s sid,...] [-u euid,...] [-U uid,...] [-G gid,...] [-t term,...] [pattern] DESCRIPTION
pgrep looks through the currently running processes and lists the process IDs which matches the selection criteria to stdout. All the cri- teria have to match. For example, pgrep -u root sshd will only list the processes called sshd AND owned by root. On the other hand, pgrep -u root,daemon will list the processes owned by root OR daemon. pkill will send the specified signal (by default SIGTERM) to each process instead of listing them on stdout. OPTIONS
-c Suppress normal output; instead print a count of matching processes. -d delimiter Sets the string used to delimit each process ID in the output (by default a newline). (pgrep only.) -f The pattern is normally only matched against the process name. When -f is set, the full command line is used. -g pgrp,... Only match processes in the process group IDs listed. Process group 0 is translated into pgrep's or pkill's own process group. -G gid,... Only match processes whose real group ID is listed. Either the numerical or symbolical value may be used. -l List the process name as well as the process ID. (pgrep only.) -n Select only the newest (most recently started) of the matching processes. -o Select only the oldest (least recently started) of the matching processes. -P ppid,... Only match processes whose parent process ID is listed. -s sid,... Only match processes whose process session ID is listed. Session ID 0 is translated into pgrep's or pkill's own session ID. -t term,... Only match processes whose controlling terminal is listed. The terminal name should be specified without the "/dev/" prefix. -u euid,... Only match processes whose effective user ID is listed. Either the numerical or symbolical value may be used. -U uid,... Only match processes whose real user ID is listed. Either the numerical or symbolical value may be used. -v Negates the matching. -x Only match processes whose name (or command line if -f is specified) exactly match the pattern. -signal Defines the signal to send to each matched process. Either the numeric or the symbolic signal name can be used. (pkill only.) OPERANDS
pattern Specifies an Extended Regular Expression for matching against the process names or command lines. EXAMPLES
Example 1: Find the process ID of the named daemon: unix$ pgrep -u root named Example 2: Make syslog reread its configuration file: unix$ pkill -HUP syslogd Example 3: Give detailed information on all xterm processes: unix$ ps -fp $(pgrep -d, -x xterm) Example 4: Make all netscape processes run nicer: unix$ renice +4 `pgrep netscape` EXIT STATUS
0 One or more processes matched the criteria. 1 No processes matched. 2 Syntax error in the command line. 3 Fatal error: out of memory etc. NOTES
The process name used for matching is limited to the 15 characters present in the output of /proc/pid/stat. Use the -f option to match against the complete command line, /proc/pid/cmdline. The running pgrep or pkill process will never report itself as a match. BUGS
The options -n and -o and -v can not be combined. Let me know if you need to do this. Defunct processes are reported. SEE ALSO
ps(1) regex(7) signal(7) killall(1) skill(1) kill(1) kill(2) STANDARDS
pkill and pgrep were introduced in Sun's Solaris 7. This implementation is fully compatible. AUTHOR
Kjetil Torgrim Homme <kjetilho@ifi.uio.no> Albert Cahalan <albert@users.sf.net> is the current maintainer of the procps package. Please send bug reports to <procps-feedback@lists.sf.net> Linux June 25, 2000 PGREP(1)
All times are GMT -4. The time now is 04:52 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy