Login or Register to Ask a Question and Join Our Community

Sponsored Content
Full Discussion: Has my script finished?
Top Forums UNIX for Dummies Questions & Answers Has my script finished? Post 20573 by Perderabo on Monday 29th of April 2002 01:06:56 PM
Old 04-29-2002
There is no perfect solution to this problem. Someone else on the system might be running an identically named script. And pids do recycle.

Here is a quick script that illustrates my solution:
Code:
#! /usr/bin/ksh

if [[ -f lockout.pid ]] ; then
        if kill -0 $(cat lockout.pid) ; then
                echo still running
                exit 0
        fi
fi
echo $$ > lockout.pid
trap "rm lockout.pid" 0
sleep 30
exit

Is the script is functioning properly, it will create and delete the lockout.pid file correctly. If the lockout.pid file exists, then the process should also exist.

If the script is abruptly killed and cannot remove the lockout.pid file then the next instance of the script will detect it. The new instance will try to send signal zero to the old pid. If the script is not running as root, it will not be able to signal another user's process.

If the previous instance of the script finished normally, the new instance of the script cannot be fooled. If the previous instance of the script is still running, the new instance of the script cannot be fooled. These are the normal conditions we expect to find.

So to fool the script, first it must abort, second the pid must have recycled and the pid must now be in use by a new, unrelated process, and third, the new process be belong to the same user that is running the script. The third condition is lifted if root runs the script.
 

10 More Discussions You Might Find Interesting

1. UNIX for Advanced & Expert Users

Finding Out When A Process Has Finished?

Problem I have an application which basically runs lots of UNIX programs remotely, using the Telnet protocol. For each program it remotely executes, it stores the process ID (PID) for that process. At regular intervals, I would like my application to take the PID for every process still... (5 Replies)
Discussion started by: 1cuervo
5 Replies

2. UNIX for Dummies Questions & Answers

background job finished notification

In my last job someone gave me the command to put in my .profile that let me know when a job I had running in the background finished. It was a word about 5 char long. I can't remember it! (4 Replies)
Discussion started by: nkeller
4 Replies

3. Shell Programming and Scripting

** Finished ** Syncid.rc

So, the script I've been working on, since I was starting to learn Shell scripting is now complete. This was coded in ksh, and I am very proud of it. What this script does, is syncs up uid's across the network. So if you have 10 servers, with 10 usernames with different UID's - this will... (1 Reply)
Discussion started by: syndex
1 Replies

4. Shell Programming and Scripting

How to know a executable has finished his task

Hi frnds, I want to know is there a way by which we can know that a C++ executable has finished its job in shell script. My task is as follows: 1.Shell script calls a executable 2.Executable executes and performs its job of generating some reports. Now i want my shell script to... (4 Replies)
Discussion started by: electroon
4 Replies

5. Shell Programming and Scripting

How do I know all processes are finished?

Hi all, I am writing a C shell script that starts a program. The program forks of several child processes. Only when all child processes are done, I want to archive my log files. Below is what I have so far, but unfortunately it doesn't work. MyProgram if (-e processes.txt) then rm... (2 Replies)
Discussion started by: Carla
2 Replies

6. Shell Programming and Scripting

check if file finished to copy

Hi all, I have a script that is monitoring a hot folder. This script works fine with one exception when the script is executed while a file is being copied to the hot folder. What is the easiest method to check if the copy file is completed? I'd like to get the solution in bash :) (8 Replies)
Discussion started by: gigagigosu
8 Replies

7. Shell Programming and Scripting

how to proceed when curl is finished

I have a script which uses cli curl to download the source code of a webpage and then tests if a specific string exists in the source. The problem is that the website has a slow response, so the eval expression hasn't completed when the test starts. The test returns a negative, and the curl... (8 Replies)
Discussion started by: locoroco
8 Replies

8. Shell Programming and Scripting

Wait until firefox has finished

I am running a macro script from the command line. But the script doesn't wait until the task has finished. firefox imacros://run/?m=macro_script.iim firefox imacros://run/?m=macro_script2.iim How do I get it to wait until the macro has been completed? I am using imacros, a firefox... (1 Reply)
Discussion started by: locoroco
1 Replies

9. Shell Programming and Scripting

How to make sure that sub shells have finished before moving on?

Hello, I have a script that is running multiple instances of an application in parallel. # learn on f0 emergent -nogui -p $ScriptLoc/$PROJ fold_tag=f0 & sleep 5 # learn on f1 emergent -nogui -p $ScriptLoc/$PROJ fold_tag=f1 & sleep 5 # learn on f2 emergent -nogui -p... (4 Replies)
Discussion started by: LMHmedchem
4 Replies

10. Shell Programming and Scripting

[BASH] Script to manage background scripts (running, finished, exit code)

Heyas, Since this question (similar) occur every now and then, and given the fact i was thinking about it just recently (1-2 weeks) anyway, i started to write something :p The last point for motivation was... (17 Replies)
Discussion started by: sea
17 Replies

LEARN ABOUT CENTOS

anacrontab

ANACRONTAB(5)							   File Formats 						     ANACRONTAB(5)

NAME

       /etc/anacrontab - configuration file for Anacron

DESCRIPTION

       The  /etc/anacrontab  configuration file describes the jobs controlled by anacron(8).  It can contain three types of lines: job-description
       lines, environment assignments, or empty lines.

       Job-description lines can have the following format:

	  period in days   delay in minutes   job-identifier   command

       The period in days variable specifies the frequency of execution of a job in days.  This variable can be represented by	an  integer  or  a
       macro (@daily, @weekly, @monthly), where @daily denotes the same value as the integer 1, @weekly the same as 7, and @monthly specifies that
       the job is run once a month, independent on the length of the month.

       The delay in minutes variable specifies the number of minutes anacron waits, if necessary, before executing a job.  This variable is repre-
       sented by an integer where 0 means no delay.

       The job-identifier variable specifies a unique name of a job which is used in the log files.

       The  command  variable specifies the command to execute.  The command can either be a command such as ls /proc >> /tmp/proc or a command to
       execute a custom script.

       Environment assignment lines can have the following format:

	  VAR=VALUE

       Any spaces around VAR are removed.  No spaces around VALUE are allowed (unless you want them to be  part  of  the  value).   The  specified
       assignment takes effect from the next line until the end of the file, or to the next assignment of the same variable.

       The  START_HOURS_RANGE  variable  defines an interval (in hours) when scheduled jobs can be run.  In case this time interval is missed, for
       example, due to a power down, then scheduled jobs are not executed that day.

       The RANDOM_DELAY variable denotes the maximum number of minutes that will be added to the delay in minutes variable which is specified  for
       each  job.   A  RANDOM_DELAY set to 12 would therefore add, randomly, between 0 and 12 minutes to the delay in minutes for each job in that
       particular anacrontab.  When set to 0, no random delay is added.

       Empty lines are either blank lines, line containing white spaces only, or lines with white spaces followed by a '#' followed  by  an  arbi-
       trary comment.

       You can continue a line onto the next line by adding a '' at the end of it.

       In  case  you want to disable Anacron, add the 0anacron cron job (which is a part of crontab(1)) into the /etc/cron.hourly/jobs.deny direc-
       tory.

EXAMPLE

       This example shows how to set up an Anacron job similar in functionality to /etc/crontab which starts all regular  jobs	between  6:00  and
       8:00 only.  A RANDOM_DELAY which can be 30 minutes at the most is specified.  Jobs will run serialized in a queue where each job is started
       only after the previous one is finished.

       # environment variables
       SHELL=/bin/sh
       PATH=/sbin:/bin:/usr/sbin:/usr/bin
       MAILTO=root
       RANDOM_DELAY=30
       # Anacron jobs will start between 6am and 8am.
       START_HOURS_RANGE=6-8
       # delay will be 5 minutes + RANDOM_DELAY for cron.daily
       1	 5    cron.daily	  nice run-parts /etc/cron.daily
       7	 0    cron.weekly	  nice run-parts /etc/cron.weekly
       @monthly  0    cron.monthly	  nice run-parts /etc/cron.monthly

SEE ALSO

       anacron(8), crontab(1)

       The Anacron README file.

AUTHOR

       Itai Tzur <itzur@actcom.co.il>

       Currently maintained by Pascal Hakim <pasc@(debian.org|redellipse.net)>.

       For Fedora, maintained by Marcela Malaova <mmaslano@redhat.com>.

cronie								    2012-11-22							     ANACRONTAB(5)
All times are GMT -4. The time now is 01:13 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy