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i know that this question has bin asked & answered a lot of times and i think i have read all of them :-( but still don't got it working :-(

OK, using CentOS release 8.2.2004 (Core) in root's cron i call a script

*/1 * * * * /bin/bash /home/getSSHsessions.sh

the script just creates a file with some process listing

[root@myhost]# cat /home/getSSHsessions.sh #!/bin/bash /usr/bin/netstat -tnpa | /usr/bin/grep "VERBUNDEN.*sshd" > /mnt/ramdisk/sshsession.ls

but the output is just a empty file

[root@myhost]# ll /mnt/ramdisk/ -rw-r--r--. 1 root root 0 5. Okt 19:33 sshsession.ls

I get crazy about that. Really don't know any more where to look.

Ah, yes, the script works fine run as user root on cmd-line. Then it creates the output as it should.

[root@myhost]# cat /home/getSSHsessions.sh #!/bin/bash /usr/bin/netstat -tnpa | /usr/bin/grep "VERBUNDEN.*sshd" > /mnt/ramdisk/sshsession.ls [root@saprouter iteanova]# /home/getSSHsessions.sh [root@myhost]# ll /mnt/ramdisk/ -rw-r--r--. 1 root root 404 6. Okt 10:46 sshsession.ls [root@myhost]# cat /mnt/ramdisk/sshsession.ls tcp 0 0 192.168.137.4:54782 192.168.137.2:80 VERBUNDEN 309654/sshd: myuser tcp 0 0 192.168.137.4:22 95.208.219.123:33300 VERBUNDEN 309622/sshd: myuser tcp 0 0 192.168.137.4:22 95.208.219.123:60744 VERBUNDEN 308085/sshd: myuser tcp 0 0 192.168.137.4:22 35.203.68.135:36564 VERBUNDEN 310513/sshd: root [
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    Is it possible that root uses English and you have to grep for connected instead of verbunden? Commented Oct 5, 2020 at 18:00
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    still, in your getSSHsessions run the command without grep so you can see the output. this will make it easier to find the cause Commented Oct 5, 2020 at 18:23
  • Check your Linux mail account. Anything that leaks out of a cron job (like stderr) is mailed to your local user. Alternatively, add a redirect 2>myCron.log to the cron entry and check the file. Commented Oct 5, 2020 at 22:41
  • As is said in the post, when starting the script as root on cmdline, i got the output as i expect. I have updated the post qwith the relevant info. Commented Oct 6, 2020 at 8:45

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OK, i got the reason of the problem.

Someone pointed me to the language settings, which was right.

It seems that in CentOS the environment between a login-shell and a non-login shell are heavily different.

While root uses german as language in root-login-shell, it is set to english in root non-login shell (shell called from cron).

:-(

and same is the output of netstat.

OK, thanks for the hint.

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