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I am trying to run a simple echo script via crontab. I set that to run every minute, but it doesn't give output on shell screen. However, it runs fine when I run the script independently.

Script

#!/bin/bash
echo "Test Script"

Crontab entry:

root@example-server ~]# cat /etc/crontab
SHELL=/bin/bash
PATH=/sbin:/bin:/usr/sbin:/usr/bin
MAILTO=root
HOME=/

# For details see man 4 crontabs

# Example of job definition:
# .---------------- minute (0 - 59)
# |  .------------- hour (0 - 23)
# |  |  .---------- day of month (1 - 31)
# |  |  |  .------- month (1 - 12) OR jan,feb,mar,apr ...
# |  |  |  |  .---- day of week (0 - 6) (Sunday=0 or 7) OR sun,mon,tue,wed,thu,fri,sat
# |  |  |  |  |
# *  *  *  *  * user-name command to be executed
  *  *  *  *  * root /root/test.sh
5
  • 2
    That's a very unique formatting style. But why do you believe the crontabbed script would write to your terminal?
    – mikeserv
    Commented Jun 20, 2015 at 0:15
  • 2
    All crontab processes are forked upon execution... Try modifying your Test Script like so: echo "Test Script" >> /var/log/crontest.log, then either go read the log in an editor or cat /var/log/crontest.log
    – eyoung100
    Commented Jun 20, 2015 at 0:59
  • hi eyoung100, when you fork a new process, does the child process inherit the stdout, stderr file descriptors of the parent cron process? of course, if cron process runs as a daemon, it may not have these file descriptors open in the first place....
    – user93868
    Commented Jun 20, 2015 at 1:36
  • i gave one upvote for the way, Todd has formatted his code....
    – user93868
    Commented Jun 20, 2015 at 1:37
  • Thank you guys. I was in impression that it will give output every minute. Commented Jun 20, 2015 at 1:46

2 Answers 2

1

The output of a cron job doesn't go to your screen. It can't — you might not even be logged in by the time the job runs!

The output of a cron job is sent via email. A working unix system always has a local email facility, which is independent of a network connection. If you want your local email to be sent to a remote account, create a .forward file in your home directory containing the remote email address. Some distributions don't set up local email by default, in which case cron output disappears in a black hole. You need a mail transfer agent to deliver local email. On an individual machine, configure it not to accept incoming connections from the network (most distributions have an easy way to set this up). Common MTAs include Exim and Postfix; if your distribution has a default MTA, just pick it.

0

you must redirect the output of echo to certain file

1.- run this command: tty

It will tell you something like /dev/pts/X Check for the number X

2.- modify your cron job with the command

crontab -e

*/1 * * * * echo "Hello every minute" > /dev/pts/X

And that's all friend.

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