Visit The New, Modern Unix Linux Community

Linux and UNIX Man Pages

Test Your Knowledge in Computers #378
Difficulty: Medium
AIX was UNIX 03 compliant.
True or False?
Linux & Unix Commands - Search Man Pages

cron(8) [v7 man page]

CRON(8) 						      System Manager's Manual							   CRON(8)

cron - clock daemon SYNOPSIS
Cron executes commands at specified dates and times according to the instructions in the file /usr/lib/crontab. 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). Crontab consists of lines of six fields each. The fields are separated by spaces or tabs. The first five are integer patterns to specify the minute (0-59), hour (0-23), day of the month (1-31), month of the year (1-12), and day of the week (1-7 with 1=monday). Each of these patterns may contain a number in the range above; two numbers separated by a minus meaning a range inclusive; a list of numbers separated by commas meaning any of the numbers; or an asterisk meaning all legal values. The sixth field is a string that is executed by the Shell at the specified times. A percent character in this field is translated to a new-line character. Only the first line (up to a % or end of line) of the command field is executed by the Shell. The other lines are made available to the command as standard input. Crontab is examined by cron every minute. FILES
/usr/lib/crontab CRON(8)

Check Out this Related Man Page

CRON(8) 						      System Manager's Manual							   CRON(8)

cron - clock daemon SYNOPSIS
auth/cron [-c] DESCRIPTION
Cron executes commands at specified dates and times according to instructions in the files /cron/user/cron. It runs only on an authentica- tion server. Option -c causes cron to create /cron/user and /cron/user/cron for the current user; it can be run from any Plan 9 machine. Blank lines and lines beginning with # in these files are ignored. Entries are lines with fields minute hour day month weekday host command Command is a string, which may contain spaces, that is passed to an rc(1) running on host for execution. The first five fields are integer patterns for minute 0-59 hour 0-23 day of month 1-31 month of year 1-12 day of week 0-6; 0=Sunday The syntax for these patterns is time : '*' | range range : number | number '-' number | range ',' range Each number must be in the appropriate range. Hyphens specify inclusive ranges of valid times; commas specify lists of valid time ranges. To run the job, cron calls host and authenticates remote execution, equivalent to running rx host command (see con(1)). The user's profile is run with $service set to rx. Cron is not a reliable service. It skips commands if it cannot reach host within two minutes, or if the cron daemon is not running at the appropriate time. EXAMPLES
Here is the job that mails system news. % cat /cron/upas/cron # send system news 15 8-17, 21 *** helix /mail/lib/mailnews % SOURCE
/sys/src/cmd/auth/cron.c SEE ALSO
con(1), rc(1) CRON(8)

15 More Discussions You Might Find Interesting

1. HP-UX

crontab issue

Dear Folks, i am new to hp-ux, i have a problem scheduling the crontab, The script is working fine at command prompt, but not working at cron, please find a solution for it , here are the logs and my schedule at cron: log after restarting crontab /var/adm/cron/log ! *** cron started *** ... (11 Replies)
Discussion started by: vaddi
11 Replies

2. Shell Programming and Scripting


Simple script that removed some files successfully as script sh -x But not working in crontab, however it fires and writes log files even some count of the files I set all env and user interaction The crontab runs in the same user where the files are there. Script: ## Set the... (11 Replies)
Discussion started by: balaji.rengaraj
11 Replies

3. Shell Programming and Scripting

CRON is not working perfectly

I scheduled a cron job to run @ 1:00 as follows , 00 01 * * * /app/cbf/CLIF/version- Please find the script. But cron is throwing a mail stating sqlplus command not found So can anybody suggest what might be the problem ??? (13 Replies)
Discussion started by: manas_ranjan
13 Replies

4. Solaris

Mail is not sent by cron daemon

Hello All, In SunOS 10, I have some cron jobs and it is running fine but the cron job outputs are not mailing to any acount of the system. In other OS, we have option like MAILTO variable or /dev/null to disable but in Sun I have no idea how it is disabled by default and how do I... (13 Replies)
Discussion started by: Tlogine
13 Replies

5. Shell Programming and Scripting

run script 1 minute interval without CronTab

I am using Solaris 9. I wish to run my script every 1 minute inteval. Though i can run it using below entry in crontab. * * * * /export/home/username/script/file_exist_& in short above script will check whether a specific file exist in a directory. If it found it will inovke another... (10 Replies)
Discussion started by: thepurple
10 Replies

6. Shell Programming and Scripting


Hi, I'm totally new to shell scripting. I need help in my crontab script. I'm trying to read some values from user (username, log file directory, server) and then use those value to create a crontab for log rotation after some interval of time. creating crontabs manually isn't big deal.... (11 Replies)
Discussion started by: MisterKhan
11 Replies

7. Shell Programming and Scripting

Script to run every 5 minutes

Hello all, I want to run a script every 5 minutes. How to accomplish this task? Thanks in advance Mrudula (12 Replies)
Discussion started by: mrudula009
12 Replies

8. Shell Programming and Scripting

Cron Job help

I need to write the cron job for the following scenario, Please help me out The CRON job runs sometime at night on Saturday and checks if there are more than eight files in the /PROCESSED folder. Any files over and above eight are deleted based on ascending order of date (eight most recent... (10 Replies)
Discussion started by: sandeep.dwivedi
10 Replies

9. Linux

cron configuration

Hi, I am programming a Western Digital ShareSpace network disk system. I installed a cron from ipkg. (explained here: ShareSpace - Hacking WD MyBook World Ed) Cron runs: /etc $ ps -fe | grep cron 6082 root 616 S < /opt/sbin/cron 18635 root ... (15 Replies)
Discussion started by: mosndup
15 Replies

10. Ubuntu

Problems with a .sh file in cron

Hi guys. This is my first post so bear with me. I'm trying to get cron to run a shell script in my home directory (/home/server) that checks the temperature of my HDD. The script works fine, however I can't run it in cron. I've checked the syslog and I have only seen two errors: - Exited with... (11 Replies)
Discussion started by: Rautoner
11 Replies

11. Shell Programming and Scripting

Grep word after last occurance of string and display next few lines

Hi, I wanted to grep string "ERROR" and "WORNING" after last occurrence of String "Starting" only and wanted to display two lines after searched ERROR and WORNING string and one line before. I have following cronjob log file "errorlog" file and I have written the code for same in Unix as below... (17 Replies)
Discussion started by: nes
17 Replies

12. UNIX for Beginners Questions & Answers

Many processes running at the same time

Hello everybody , I launched cron to execute a task every hour but the job takes more than hour that's why I'm getting more than 1000 cron processes running at the same time !!! My question is how to tell cron not to execute unless the job terminated in order to have only one process running .... (14 Replies)
Discussion started by: beautymind
14 Replies

13. Shell Programming and Scripting

Statement returning error only launching the sh script via crontab

hi all, I created a sh script to import some tables from mysql to hive. No problem launching it manually, but if I schedule via crontab it returns me an error in the following part: #create an array containing all the tables for $dbname query="SELECT table_name FROM information_schema.tables'... (10 Replies)
Discussion started by: mfran2002
10 Replies

14. UNIX for Beginners Questions & Answers

Cron job scheduled is running once, but reports are generating twice

Team, Hope you all are doing fine I have one admin server which is being used dedicately to run cron jobs on hourly basis, fetching the details from Database which is in a different server.These cronjob are run on every hourly/5 minutes basis depending as per end user requirement.The script... (12 Replies)
Discussion started by: whizkidash
12 Replies

15. Shell Programming and Scripting

Script that will look the same as Cron

Hi All,. need your expertise, is there a way to create a script that will run with specific time without using cron. because i dont have access in cron. TIA (19 Replies)
Discussion started by: meister29
19 Replies

Featured Tech Videos