I wrote a script for server monitoring. Its working fine. Now i have to make to run for each 30 min. I tried cron by following steps.

1.crontab -e

2.*/30 * * * * /shellscript/finalnew.sh

3.save and exit by Esc+:wq+enter

4.i saw this message "crontab: installing new crontab"

5.I checked by crontab -l


It too showed all. But instead of running that script, The cron sends a mail as follows

From root@qmail.com Tue Nov 20 22:28:06 2007
Date: Tue, 20 Nov 2007 22:28:01 +0530
From: root@qmail.com (Cron Daemon)
To: root@qmail.com
Subject: Cron <root@qmail> /shellscript/finalnew.sh
X-Cron-Env: <SHELL=/bin/sh>
X-Cron-Env: <HOME=/root>
X-Cron-Env: <PATH=/usr/bin:/bin>
X-Cron-Env: <LOGNAME=root>
X-Cron-Env: <USER=root>

/bin/sh: /shellscript/finalnew.sh: No such file or directory


I know this is very very worst fault by me. But please bear it n help me.....

Hi,

Cron tells you that it cannot find /shellscript/finalnew.sh

Are you sure this script is called finalnew.sh (uppercase/lowercase )and can be found in /shellscript ?

First of all the crontab entry is incorrect, the format for the
time is invalid. Look at the man-page.


And does the script ind that path exist, is it readable by the
user that owns the crontab?


Cheers,
Tink

Blender mistake was my mine.. I told the path wrongly to cron. But time entry is correct. I saw that from http://www.reallylinux.com/docs/basiccron.shtml

But only one more error is coming. The script is not running. Its sending mail only. its telling that
"TERM environment variable not set."

Hi,

If you run a script from cron the environment for the user running that script is not set .

You can let the script check if it is run from a terminal or not. If not, the environment is parsed. Something like this:

# Needed due to crontab behavior: parse user profile if needed
[[ "`/usr/bin/tty`" == "not a tty" ]] && . ~/.profile

Check if ~/.profile is the file to parse. It could be ~/.bash_profile (or alike).

Hope this helps.

Sorry i cant get u. Can u please tell what exactly i have to do now....

Hi,

If you run a script from a terminal/xterm it (the script) can access certain environment variables (like TERM, the variable you mentioned in post #4). If you run a script from cron, there is no environment (TERM isn't present, to name just one).

Try these commands from an xterm:

echo $TERM

and

env

All the output is part of a users environment. Almost all of it is not present when you run a script from cron.

If you put the 2 lines I posted in the beginning of your finalnew.sh script (after the hash-bang [#!/bin/bash]), the environment will be parsed if it is run from cron.

[[ "`/usr/bin/tty`" == "not a tty" ]] This part checks if the script is run from a terminal. If it is true (&&) the environment will be parsed (. ~/.profile).

You need to check if you use ~/.profile or ~/.bash_profile. Use the one you have.

Something like this:

I started my script like this
#!/bin/bash
# Needed due to crontab behavior: parse user profile if needed
[[ "`/usr/bin/tty`" == "not a tty" ]] && . ~/.bash_profile

TERM=linux
export TERM
.
.
.
.
rest of my script
.
.
.
exit 0

The cron is executing the script in proper intervals but it mails the result of the script to root.(i am executing as root it self)

I thought i used several echo commands in that script to check in terminal. But while running from cron, it sends the output as mail. So i commented all echo. But cron is throwing empty mails to root.

Somebody please help me.

Finally i ran env command n copied all of them in the beginning of my script. Still it throwing empty mails to root whenever cron runs the script.

#!/bin/bash

[[ "`/usr/bin/tty`" == "not a tty" ]] && . ~/.bash_profile
HOSTNAME=qmail.com
TERM=xterm
SHELL=/bin/bash
SSH_TTY=/dev/pts/1
USER=root
KDEDIR=/usr
MAIL=/var/spool/mail/root
PATH=/usr/kerberos/sbin:/usr/kerberos/bin:/usr/local/sbin:/usr/local/bin:/sbin:/ bin:/usr/sbin:/usr/bin:/usr/X11R6/bin:/root/bin
INPUTRC=/etc/inputrc
PWD=/root
LANG=en_US.UTF-8
SSH_ASKPASS=/usr/libexec/openssh/gnome-ssh-askpass
SHLVL=1
HOME=/root
LOGNAME=root
SSH_CONNECTION=::ffff:192.168.0.218 4676 ::ffff:192.168.0.222 22
LESSOPEN=|/usr/bin/lesspipe.sh %s
G_BROKEN_FILENAMES=1
_=/bin/env

TERM=linux
export TERM
clear


touch mailcontent.txt
flag1=0
flag=0 #initialze a flag

sleep 1

if [ "$(nmap -P0 -p25 1.2.3.4 | grep open)" ] #port check
then
flag1=0 #dummy
else
flag=1 #set flag
echo SMTP seems not open in 1.2.3.4, Please check \n >> mailcontent.txt #update error file
fi

sleep 1

if [ "$(nmap -P0 -p110 1.2.3.4 | grep open)" ]
then
flag1=0
else
echo POP seems not open in 1.2.3.4, Please check \n >> mailcontent.txt
flag=1
fi
.
.
.
.
like this many servers
.
.
.
.
.
.

if [ $flag -eq 1 ] ;
then
mail -s "First level warning" root@qmail.com < mailcontent.txt
else
flag1=0
fi

rm mailcontent.txt





This is my script. Please tell me why its throwing empty mails to root.....Please i am struggling for a long time.............

A cron job does NOT have an interactive terminal attached, it's a detached background process, therefore the clear cmd is pointless .... (hint)

Thank u very much. Now my script is running. The lesson is we must not use any screen based command like echo, clear while writing a script for cron..... Thank u all again.