Best of Technical Support
I'm having trouble using the crontab file. This is the first time I have tried it and have not been able to get it working. The daemon crond is running. In my crontab file I have the following line:
30 6 * * * /home/Talon/automail
automail is a shell script to log on to my Internet provider, get my mail and log off. As far as I can tell crond never executes this command. —Jeff Largent
Are you sure your automail program is executable? If it isn't, type:
chmod +x /home/Talon/automail
—Pierre Ficheux, Lectra Systèmès email@example.com
When I try to mount /dev/fd0 I get the following error message:
/dev/fd0 is not a block device
What does that mean and how do I fix it? I can fdformat a floppy, but I can't mount or create a file system on one. —Scott Petinga
Check out the type of /dev/fd0—it should be a block device. If it is properly identified, the leading character for this device in the directory list will be a b. For example:
$ ls -l /dev/fd0 brwxrwxrwx 1 root floppy 2, 0 Jul 18 1994 /dev/fd0
If the b is not present, re-create the device by typing:
rm /dev/fd0 mknod /dev/fd0 b 2 0—Pierre Ficheux, Lectra Systèmès firstname.lastname@example.org
Every time I start up the X program netcfg, it generates a zombie process. I haven't been able to get rid of it. Nobody in my dorm can figure this out either. —Scott
netcfg is a python script that Red Hat created to ease the configuration of network parameters. This script has been expanded and had many bugs fixed since 4.1 was released.
I suggest you upgrade to the latest netcfg-rpm (which is netcfg-2.15-1.i386.rpm as of this writing). —Mario de Mello Bittencourt Neto, Argo Internet email@example.com
How do I limit the size of a directory? I want to limit each customer's directory to 1MB. If a customer attempts to upload 2MB of content via ftp, I want Linux to reject the attempt to store more than 1MB. How do I accomplish this disk management feat? —M. Lamberson
This is easy. Install the quota support that will allow you to control the maximum size of a user's home directory. Assuming that you have FTP configured to redirect non-anonymous FTP logins to the actual home directory, it is simply a matter of configuring quota support in your kernel. Just go to /usr/src/linux and type:
Under the Filesystems entry, check for quota support. Recompile the kernel, reboot and you can configure quota as you wish. —Mario de Mello Bittencourt Neto, Argo Internet firstname.lastname@example.org
What do the different run levels listed by the init command do? I have looked in various Unix books and also in Linux Configuration and Installation, but I can't find any information. —Paul Sutton
A Unix run level is a state of system configuration. Each level signifies a certain level of operation. The run levels are controlled (and are relevant to) the init daemon, which is the first process that is executed when any Unix system is first loaded.
init's job is to start and stop processes, and the run levels help determine which to control. The file /etc/inittab contains entries that init uses to decide which processes to start and how to start them. An entry looks like this:
NM is a two-letter identifier for the command—each command must have its own, unique identifier. LEVs is a list of levels during which to run the command. It is typically a number or set of numbers from 0-5 but can also be an S or even nothing, depending on your version of init. WHEN_AND_HOW is an option specifying when the command should be run, whether init should wait for it to finish or not, whether it should be restarted when it dies and so on. COMMAND is the full path and file name of the command to execute.
The run level corresponds to the LEVs list. For example, the following lines are in my inittab file:
# Start the local dial-in services s0:45:respawn:/usr/local/sbin/mgetty ttyS0 \ vt100 -D -x 0 s1:45:respawn:/usr/local/sbin/mgetty ttyS2 \ vt100 -D -x 0
I have defined two processes, s0 and s1, which will be executed any time the system is in run levels 4 or 5. The respawn option tells init to re-execute the command when the command terminates. (This allows my dial-in lines to accept the new callers when users hang up.) Finally, you can see the command that is run for each entry.
By using run levels, a system administrator can configure a system to automatically start and stop certain processes when they put their systems into different run levels. The most common use for this capability is to have a normal, multi-user level and a single-user administration level. By triggering this level, they can have their servers automatically terminate user processes and disable network support in order to administer their systems.
You can get more information on Unix run levels from the INIT(8) and INITTAB(5) man pages. Since many different Unix flavors exist, there are also many different versions of init. So, you should examine your man pages for exact details. —Chad Robinson, BRT Technical Services Corporation email@example.com
Fast/Flexible Linux OS Recovery
On Demand Now
In this live one-hour webinar, learn how to enhance your existing backup strategies for complete disaster recovery preparedness using Storix System Backup Administrator (SBAdmin), a highly flexible full-system recovery solution for UNIX and Linux systems.
Join Linux Journal's Shawn Powers and David Huffman, President/CEO, Storix, Inc.
Free to Linux Journal readers.Register Now!
- Download "Linux Management with Red Hat Satellite: Measuring Business Impact and ROI"
- Profiles and RC Files
- Astronomy for KDE
- Understanding Ceph and Its Place in the Market
- Maru OS Brings Debian to Your Phone
- Snappy Moves to New Platforms
- Git 2.9 Released
- What's Our Next Fight?
- OpenSwitch Finds a New Home
- The Giant Zero, Part 0.x
With all the industry talk about the benefits of Linux on Power and all the performance advantages offered by its open architecture, you may be considering a move in that direction. If you are thinking about analytics, big data and cloud computing, you would be right to evaluate Power. The idea of using commodity x86 hardware and replacing it every three years is an outdated cost model. It doesn’t consider the total cost of ownership, and it doesn’t consider the advantage of real processing power, high-availability and multithreading like a demon.
This ebook takes a look at some of the practical applications of the Linux on Power platform and ways you might bring all the performance power of this open architecture to bear for your organization. There are no smoke and mirrors here—just hard, cold, empirical evidence provided by independent sources. I also consider some innovative ways Linux on Power will be used in the future.Get the Guide