Sponsored Content
Top Forums Shell Programming and Scripting Script that will look the same as Cron Post 303037692 by meister29 on Friday 9th of August 2019 11:31:40 AM
Old 08-09-2019
Quote:
Originally Posted by drysdalk
Hello,

OK, here's a quick hacked-together version of a script that more-or-less does what crond would do. As Neo has mentioned however, this is not the best idea, as you're kind of needlessly re-inventing something that already exists and which will definitely do a far better job than this shell script. If the customer/client/maintainer/whoever actively doesn't want you running scheduled tasks on the server, then they're not going to be happy about you doing it no matter how you go about doing it. Alternatively if you have a hard requirement to run scheduled tasks and the customer just doesn't want you installing software, then you need to have a conversation with your customer explaining that they need to install crond to enable you to do the work that you've been asked to do, otherwise you can't do it. If the job you need to do has a 100% requirement for scheduled tasks, then whoever provides this system either has to install or let you install crond, or they need to accept that the job can't be done since they won't let you have the tools you need to do it.

Anyway - bearing in mind all the above caveats (and the potential no doubt for bugs and issues that could be lurking with this approach), here's a quickly knocked-together script that would do more or less what you need.

Code:
$ cat cron.tab
Fri,16,13,echo "It's thirteen minutes past four !"
Fri,16,15,echo "It's quarter past four !"
$ cat script3.sh
#!/bin/bash

crontab=/home/unixforum/282472/cron.tab

while true
do
        while read cron
        do
                runday=`echo "$cron" | /usr/bin/awk -F, '{print $1}'`
                runhour=`echo "$cron" | /usr/bin/awk -F, '{print $2}'`
                runminute=`echo "$cron" | /usr/bin/awk -F, '{print $3}'`
                runcommand=`echo "$cron" | /usr/bin/awk -F, '{print $4}'`

                nowday=`/usr/bin/date +%a`
                nowhour=`/usr/bin/date +%H`
                nowminute=`/usr/bin/date +%M`

                if [ "$runday" == "$nowday" ] && [ "$runhour" == "$nowhour" ] && [ "$runminute" == "$nowminute" ]
                then
                        /usr/bin/date
                        $runcommand
                fi
        done < "$crontab"

        /usr/bin/sleep 60
done

$ date
Fri Aug  9 16:11:14 BST 2019
$ ./script3.sh
Fri Aug  9 16:13:16 BST 2019
"It's thirteen minutes past four !"
Fri Aug  9 16:15:16 BST 2019
"It's quarter past four !"
^C
$

thank you very much sir. i will take note of that. from here i will create my own. thx thx..
 

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

Cron Script Q

When logged in as root if I type "env" there are a bunch of environment settings including one for CLASSPATH. However, I ran a cron script that ran this command "env > cronEnv". I noticed that the environment variables were entirely different inside the script. There wasn't even a CLASSPATH... (2 Replies)
Discussion started by: doublek321
2 Replies

2. UNIX for Dummies Questions & Answers

Cron + Script = No Output?

I've got an *extremely* simple script I want to run every minute: #!/bin/sh ping -c 1 192.168.1.20 > ~/onlinestatus.txt So, the script is called "status", it's executable, and in the correct path, etc. In a terminal window (I'm using Mac OS X), I can type status, and it will create... (4 Replies)
Discussion started by: jmf77
4 Replies

3. AIX

problem with a script and the cron

hello I use a script to give me the number of users, at each hour. this script read a file where there is the number of users for each hour and for each month (so 12 files per year). If i execute the script (root), it is ok, i have xxx users for each hour. if I put the script in the cron... (1 Reply)
Discussion started by: pascalbout
1 Replies

4. Shell Programming and Scripting

script not working in CRON

guys i have written a very simple script .it runs manually well. but when i put it in cron,it doesn't give the desired output. script looks like this: #! /usr/bin/sh #script for loading data in table using ctl file/Abhijeet K/08.07.2006 /svm_wl1/. .profile cd... (5 Replies)
Discussion started by: abhijeetkul
5 Replies

5. Solaris

Need to cron the script

I want to cron one script which should run every second Thursday (in general Nth occurence of any day) of every month. I am not getting the exact idea of doing this; Please guide. Regards, (3 Replies)
Discussion started by: jaiankur
3 Replies

6. Shell Programming and Scripting

how to run script? call other script? su to another user? make a cron?

Good morning. I am searching for "how-to"'s for some particular questions: 1. How to write a script in HP-UX 11. 2. How to schedule a script. 3. How to "call" scripts from the original script. 4. How to su to another user from within a script. This is the basics of what the... (15 Replies)
Discussion started by: instant000
15 Replies

7. Solaris

Script for cron

Dear All, I have an assignment about collecting /var/adm/messages on each server running Solaris 9. All these servers will be installed with a script that collect all the messages in cron. All the messages will be collected by a single server. I have a script to collect all the messages, but... (2 Replies)
Discussion started by: frankoko
2 Replies

8. Shell Programming and Scripting

cron a script

This has to be the ultimate newbie question... I have a script that works well. To run it, I cut and paste it into a putty session. Is there a way to put the script into a file and just run that file -- like a DOS batch file? I'd like to schedule the file to run daily. Thanks,... (3 Replies)
Discussion started by: landog
3 Replies

9. UNIX for Dummies Questions & Answers

Execution problem with Cron: Script works manually but not w/Cron. Why?

Hello gurus, I am making what I think is a simple db2 call from within a shell script but I am having difficulty producing the desired report when I run the script shown below from a shell script in cron. For example, my script and the crontab file setup is shown below: #!/bin/ksh db2... (3 Replies)
Discussion started by: okonita
3 Replies

10. Shell Programming and Scripting

Script in cron

I have a script that require input from terminal at some point (either a,b or c) How can I cron the script and automatically assume c as the input. (2 Replies)
Discussion started by: aydj
2 Replies
CRONTAB(1)						    BSD General Commands Manual 						CRONTAB(1)

NAME
crontab -- maintain crontab files for individual users (V3) SYNOPSIS
crontab [-u user] file crontab [-u user] { -l | -r | -e } DESCRIPTION
The crontab utility is the program used to install, deinstall or list the tables used to drive the cron(8) daemon in Vixie Cron. Each user can have their own crontab, and they are not intended to be edited directly. (Darwin note: Although cron(8) and crontab(5) are officially supported under Darwin, their functionality has been absorbed into launchd(8), which provides a more flexible way of automatically executing commands. See launchctl(1) for more information.) If the /usr/lib/cron/cron.allow file exists, then you must be listed therein in order to be allowed to use this command. If the /usr/lib/cron/cron.allow file does not exist but the /usr/lib/cron/cron.deny file does exist, then you must not be listed in the /usr/lib/cron/cron.deny file in order to use this command. If neither of these files exists, then depending on site-dependent configuration parameters, only the super user will be allowed to use this command, or all users will be able to use this command. The format of these files is one username per line, with no leading or trailing whitespace. Lines of other formats will be ignored, and so can be used for com- ments. The first form of this command is used to install a new crontab from some named file or standard input if the pseudo-filename '-' is given. The following options are available: -u Specify the name of the user whose crontab is to be tweaked. If this option is not given, crontab examines ``your'' crontab, i.e., the crontab of the person executing the command. Note that su(1) can confuse crontab and that if you are running inside of su(1) you should always use the -u option for safety's sake. -l Display the current crontab on standard output. -r Remove the current crontab. -e Edit the current crontab using the editor specified by the VISUAL or EDITOR environment variables. The specified editor must edit the file in place; any editor that unlinks the file and recreates it cannot be used. After you exit from the editor, the modified crontab will be installed automatically. FILES
/usr/lib/cron/cron.allow /usr/lib/cron/cron.deny DIAGNOSTICS
A fairly informative usage message appears if you run it with a bad command line. SEE ALSO
crontab(5), compat(5), cron(8), launchctl(1) STANDARDS
The crontab command conforms to IEEE Std 1003.2 (``POSIX.2''). The new command syntax differs from previous versions of Vixie Cron, as well as from the classic SVR3 syntax. AUTHORS
Paul Vixie <paul@vix.com> BSD
December 29, 1993 BSD
All times are GMT -4. The time now is 09:59 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy