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Eric Leschinski's questions

Martin Hope
Eric Leschinski
Asked: 2012-11-17 20:51:50 +0800 CST
  • 361

This is a Canonical Question about using cron & crontab.

You have been directed here because the community is fairly sure that the answer to your question can be found below. If your question is not answered below then the answers will help you gather information that will help the community help you. This information should be edited into your original question.

The answer for 'Why is my crontab not working, and how can I troubleshoot it?' can be seen below. This addresses the cron system with the crontab highlighted.

linux cron
Martin Hope
Eric Leschinski
Asked: 2012-10-24 07:51:08 +0800 CST
  • 1

I want to allow users to control the em1 device in Linux:

When I run this command:

ifdown em1

em1 is the embedded ethernet card 1, I want the user to be able to turn off the ethernet card.

On Fedora 17, I get this error message:

Users cannot control this device

I want a certain user to be able to run a certain command on Linux without giving rights to other users. What is the best way to do that?

linux
Martin Hope
Eric Leschinski
Asked: 2012-10-24 06:17:01 +0800 CST
  • 2

I have a fresh install of Fedora 17 installed, 64 bit. Everything works flawlessly, It connects to the internet automatically when I plug in the internet cable.

So I'm kind of confused when I issue this command:

el@defiant ~ $ ifconfig eth0

And I get the error:

eth0: error fetching interface information: Device not found

Device not found? Here is ifconfig:

ifconfig

I get this:

em1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
    inet 192.168.1.102  netmask 255.255.255.0  broadcast 192.168.1.255
    inet6 fe80::ea40:f2ff:fee1:58c  prefixlen 64  scopeid 0x20<link>
    ether e8:40:f2:e1:05:8c  txqueuelen 1000  (Ethernet)
    RX packets 44753  bytes 51284267 (48.9 MiB)
    RX errors 0  dropped 0  overruns 0  frame 0
    TX packets 34222  bytes 4294174 (4.0 MiB)
    TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
    device interrupt 20  memory 0xf7d00000-f7d20000  

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 16436
    inet 127.0.0.1  netmask 255.0.0.0
    inet6 ::1  prefixlen 128  scopeid 0x10<host>
    loop  txqueuelen 0  (Local Loopback)
    RX packets 5152  bytes 1263744 (1.2 MiB)
    RX errors 0  dropped 0  overruns 0  frame 0
    TX packets 5152  bytes 1263744 (1.2 MiB)
    TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

So, it appears that someone has changed the old eth0 to em1 since earlier versions of Fedora (Fedora 8 is the last I know which used eth0). If I do the command: ifconfig em1 then I get something similar to the old ifconfig eth0. But why the name change?

My question is why was eth0 changed to em1 and what the heck does em from em1 mean?

linux