Sponsored Content
Top Forums UNIX for Dummies Questions & Answers What crontab is in effect after reboot Post 302484213 by methyl on Thursday 30th of December 2010 06:45:53 AM
Old 12-30-2010
Quote:
Which is the preferred method to modify crontabs. To issue the crontab –e or to edit the file and reset it using the crontab [filename] method?
Personally I always extract a crontab file twice to an editing area using "crontab -l" redirected once under its correct name and once with a date suffix.

I never use "crontab -e" and prefer to edit the crontab in the editing area under its correct name with say "vi" and then finally publish the end-product with "crontab". At the final publish stage the "crontab" command validates the file.

There are several advantages with this approach:

1) You always have a backup. (It is remarkably easy to wipe a crontab file).

2) You have before and after files which you can check with "diff" before publishing the crontab.

3) You have control over when your crontab becomes live. I have prepared and checked an edited crontab in advance by this method. I have also taken lines from a test system crontab and injected them into the live crontab by this method.

4) You create an archive of changes which can be useful for looking up what you did last time.

5) On some sites such an audit trail is mandatory.
This User Gave Thanks to methyl For This Post:
 

9 More Discussions You Might Find Interesting

1. UNIX for Dummies Questions & Answers

recursive effect!!

I run the following command in some of my folders... and ended up with a huge mess!! find . -type f -exec perl -e 's/blabla/zzzxxxx/gi' -p -i.bak {} \; I had to kill the process and later when I checked with one of my folders.. ls vaditerm.dt.bak vaditerm.dt.bak.bak... (2 Replies)
Discussion started by: sskb
2 Replies

2. UNIX for Advanced & Expert Users

Effect of Preemptive Kernel

hi there, i am porting kernel 2.2 driver program to kernel 2.6. for some extent i am successfull but some times the system gets hanged. what might be the problem? i am not able to get any help from log messages as nothing is being printed at that moment. hey does this kernel preemptiveness and... (2 Replies)
Discussion started by: sriram.ec
2 Replies

3. UNIX for Dummies Questions & Answers

How do properties effect script?

Hi, I have noticed that rm -if will perform completely different to rm -fi. Whats the pattern of how I put my options to the script in relation to how it will act. i.e rm -fi treat the remove as interative but rm -if treats it as forced Thansk, Chris. (1 Reply)
Discussion started by: Chiefos
1 Replies

4. Solaris

different between soft reboot and hard reboot

Hi Guru's Can any want here could explain to me the different between soft reboot and hard reboot . Best Regards Seelan (3 Replies)
Discussion started by: seelan3
3 Replies

5. Solaris

will this script in crontab effect SUN 9??

Hi all, I work in Sun Solaris 9. I am plan to put the following script(remove90dysOldrfiles.sh) in CRONTAB for removing huge huge number of files those are older than 90 days from different directory. In the Crontab i will set the time for everymidnight it will search 90days older file and... (2 Replies)
Discussion started by: thepurple
2 Replies

6. Virtualization and Cloud Computing

The Network Effect - Part 1

2008-10-31T22:46:14+01:00 http://geekandpoke.typepad.com/.a/6a00d8341d3df553ef010535ce543e970c-800wi Nicholas Carr (and here) has some problems with Tim O'Reilly's theory about the cloud and the network effect. http://feeds.feedburner.com/~f/GeekAndPoke?i=OFn0M... (0 Replies)
Discussion started by: Linux Bot
0 Replies

7. UNIX for Advanced & Expert Users

CRONTAB does not run since reboot

Hi, we reboot our Linux server yesterday and since then (specialy last night) no job from crontab has run. Any idea ? What should I look for to investigate? Many thanks. (5 Replies)
Discussion started by: big123456
5 Replies

8. Shell Programming and Scripting

how to give dictionary effect ?

Hello, In google: if we type the text like :- It gives us a question saying :- I want to know how to write a shell script to give this Dictionary effect. example:If we give "lst" then it corrects us saying "list". Can you please help me with a sample code! friends..... (3 Replies)
Discussion started by: nsharath
3 Replies

9. HP-UX

Old crontab file reflected after server reboot

Hi All, We are working on HP_UNIX. I am facing a strange problem regarding crontab in our unix environment.Whenever a server reboot takes place on our server the old crontab gets reflected due to which several scripts which were earlier uncommented starts running causing a huge problem .Is... (6 Replies)
Discussion started by: ammbhhar
6 Replies
CRON(8) 						      System Manager's Manual							   CRON(8)

NAME
cron - clock daemon SYNOPSIS
/usr/sbin/cron DESCRIPTION
Cron executes commands at specified dates and times according to the instructions in the files /etc/crontab and /etc/crontab.local. None, either one, or both of these files may be present. Since cron never exits, it should only be executed once. This is best done by running cron from the initialization process through the file /etc/rc; see init(8). The crontab files consist of lines of seven fields each. The fields are separated by spaces or tabs. The first five are integer patterns to specify: o minute (0-59) o hour (0-23) o day of the month (1-31) o month of the year (1-12) o day of the week (1-7 with 1 = Monday) Each of these patterns may contain: o a number in the range above o two numbers separated by a minus meaning a range inclusive o a list of numbers separated by commas meaning any of the numbers o an asterisk meaning all legal values The sixth field is a user name: the command will be run with that user's uid and permissions. The seventh field consists of all the text on a line following the sixth field, including spaces and tabs; this text is treated as a command which is executed by the Shell at the specified times. A percent character (``%'') in this field is translated to a new-line character. Both crontab files are checked by cron every minute, on the minute. FILES
/etc/crontab /etc/crontab.local 7th Edition October 23, 1996 CRON(8)
All times are GMT -4. The time now is 08:21 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy