[solved]
Running Centos 7.
I have a cron that I want to test so I am running it every minute until I have it debugged.

It does not work.

#crontab -e
* * * * * /home/cwc/scripts/logfile.sh

Here is the script which resides in /home/cwc/scripts/. The script works.

#!/bin/sh
NOW=$(date +"%Y-%m-%d_%H%M%S");
LOGFILE="log-$NOW.txt";
/usr/bin/nmap -sP 192.168.1.0/24 >> /home/cwc/html/logs/$LOGFILE;

It doesn't work, do you mean that the cron tab script is not executed?

It doesn't do the desired output? or what?

I do not get the desired output.
If the script is executed manually it works but not from cron.

Thanks.

Have you tried running it let's say an interval of 5 minutes? Just try whether what you expect will work.

When you run things from CRON your environment variables are different then when you run them directly.

Most likely /home/cwc/scripts/logfile.sh is relying on one or more of these environment variables. Could be that PATH is different, or something that normally gets set in .bashrc ...

Edit: Ignore this comment. I missed that you posted the contents of the script. Habitual is right ...

Scanning 254 hosts every minute of every day?

http://www.dataphyx.com/cronsandbox/cronsandboxgui.php

It takes me upward of 30 minutes to scan 192.168.1.0/24

-sP just pings the hosts and does not scan ports. It should only take seconds to complete.

Your script works as is on my CentOS 7 system from cron. How are you running it from the command line? Is it executable?

stupid question, but did you restart crond after setting the cron?

if you've done that, make the file executable and add sh before the command

If you add a user job via crontab -e restarting crond is not necessary.

Adding sh before the script is also not necessary, as the first line in your batch file has specified that already.

I tried it on my computer and it seems to work as well. In order to debug it any further you need to give more info. For example, what is the expected output, what output are you getting. Are you getting a separate file for each minute. Are they all the same?

One comment is that you've specified /bin/sh, but are using bash specific commands like $(). You should use /bin/bash instead. It might work the way you've written it, but it doesn't have to ...

Try running the script using /bin/env.
This will create a fresh environment.

You can also set environment variables with env if necessary.

Thanks! I blinked and it was over.

*/30 * * * * /bin/bash -l /home/cwc/bash/makelogs.sh


script:

#!/bin/bash
NOW=$(date +"%Y-%m-%d-%T");
LOGFILE="log-$NOW.txt";
/usr/bin/nmap -sP 192.168.1.0/24 > /home/cwc/html/logs/$LOGFILE;



Thanks for all the tips.

You could use "#!/bin/bash -l" on the first line of your script. Though I see nothing that would require you to use the login option. It's good to read "man 5 crontab" and "man crontab" to understand how the execution occurs including the environment.