Best of Technical Support
I'm running a small private LAN with Linux Red Hat 7.0. The following command was entered on system “lucy”, with the resultant message:
[root@lucy]# tar cvf testbed:/home/someuser file.txt Permission denied. tar: testbed\:/home/someuser: Cannot open: Input/output error tar: Error is not recoverable: exiting now
This output is from the /var/log/messages file on the system “testbed”:
Mar 30 08:14:57 testbed pam_rhosts_auth: denied to root@lucy as root: access not allowed Mar 30 08:14:57 testbed in.rshd: rsh denied to root@lucy as root: Permission denied. Mar 30 08:14:57 testbed in.rshd: rsh command was '/etc/rmt'I have been reading about PAM but have not figured it out yet. Could someone give me assistance to make this command work? I don't mind if I temporally dummy up my security in /etc/pam.d, but my last attempt made it impossible to even log in. Ouch! —Les Hilliard, firstname.lastname@example.org
On the machine where you want to put the tar file, create a .rhosts file in the home directory, with 0400 permissions. The .rhosts file should a single line, “X.X.X.X user”, where X.X.X.X is the IP address of the machine where the tar command is run and the user is the user id of the person running the command. Run the following command on the other machine:
tar -cvf root@mm:/root/aaa.tar work/
where mm is the remote machine name or IP address and work is the local directory. Beware that this will also allow rlogin without a prompt for password. —Usman S. Ansari, email@example.com
I recently installed Netscape 4.7.6 on my Linux machine (the machine was recently rebuilt, so the kernel and libraries are very recent). When I was trying to run it, I got the following error message:
/usr/local/bin/netscape /usr/local/bin/netscape: error in loading shared libraries: libstdc++-libc6.1-1.so.2: cannot open shared object file: No such file or directory
Checking my libraries confirmed that I didn't have that particular library installed, but a newer one:
# cd /usr/lib # ls libstdc++* libstdc++-3-libc6.1-2-2.10.0.a libstdc++.a.2.10.0 libstdc++-3-libc6.1-2-2.10.0.so libstdc++-libc6.1.so libstdc++-libc6.1-2.a.3 libstdc++-libc6.1-2.so.3I successfully resolved the problem by providing a symbolic link to the newer library:
# ln -s libstdc++-libc6.1-2.so.3 libstdc++-libc6.1-1.so.2This solved the problem, and Netscape is running smoothly. However, this incident left me with a number of questions:
What is the meaning of the .2 and .3 at the end of the filename?
Is this solution appropriate? I would have liked to create a shorter link, like libstdc++-libc6.1.so, but that didn't work. Would it have been more appropriate to actually find libc6.1-1 and install it next to the existing one?
My assumption is the Netscape binaries had the library version hardcoded (I believe this version of Netscape is not available as source code); is that correct? —Michael, firstname.lastname@example.org
The reason a library maintainer changes a revision is there is a significant change in the underlying code or interface. The maintainer usually feels it would not be wise for a program dynamically linked with an older version of the library to automatically work with the newer version. “Appropriate” is in the eyes of the beholder. It is possible that the dynamically linked program you are “tricking” could disastrously crash, destroying itself and other things. Most likely, though, it won't. But, it definitely would be safer to find the actual dynamically linked library. The Netscape 4.x binaries have some interfaces (to the dynamically linked library) and versions hard coded. —Christopher Wingert, email@example.com
I am currently using Mandrake 7.2 as a server platform. I do not want to run X. I have tried all configuration options on the Mandrake install, and even manually deselected X components, but the install just goes ahead and installs X anyway. Is there a way of stopping X and X components from being installed?
Also, when in console mode, is there a way to stop the monitor from going into power save mode? I have disabled the apm dæmon and power management in the BIOS, but the monitor keeps shutting down. —Gerard Nicol, firstname.lastname@example.org
Use rpm -qa to uninstall packages you may not need. You should also keep a list of the packages you uninstall so you can install them again, if needed. To disable power saving in the console, do setterm -blank 0. —Usman S. Ansari, email@example.com
Practical Task Scheduling Deployment
One of the best things about the UNIX environment (aside from being stable and efficient) is the vast array of software tools available to help you do your job. Traditionally, a UNIX tool does only one thing, but does that one thing very well. For example, grep is very easy to use and can search vast amounts of data quickly. The find tool can find a particular file or files based on all kinds of criteria. It's pretty easy to string these tools together to build even more powerful tools, such as a tool that finds all of the .log files in the /home directory and searches each one for a particular entry. This erector-set mentality allows UNIX system administrators to seem to always have the right tool for the job.
Cron traditionally has been considered another such a tool for job scheduling, but is it enough? This webinar considers that very question. The first part builds on a previous Geek Guide, Beyond Cron, and briefly describes how to know when it might be time to consider upgrading your job scheduling infrastructure. The second part presents an actual planning and implementation framework.
Join Linux Journal's Mike Diehl and Pat Cameron of Help Systems.
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|The Firebird Project's Firebird Relational Database||Jul 29, 2016|
|Stunnel Security for Oracle||Jul 28, 2016|
|SUSE LLC's SUSE Manager||Jul 21, 2016|
|My +1 Sword of Productivity||Jul 20, 2016|
|Non-Linux FOSS: Caffeine!||Jul 19, 2016|
|Murat Yener and Onur Dundar's Expert Android Studio (Wrox)||Jul 18, 2016|
- The Firebird Project's Firebird Relational Database
- Stunnel Security for Oracle
- My +1 Sword of Productivity
- Non-Linux FOSS: Caffeine!
- SUSE LLC's SUSE Manager
- Managing Linux Using Puppet
- Murat Yener and Onur Dundar's Expert Android Studio (Wrox)
- Parsing an RSS News Feed with a Bash Script
- Google's SwiftShader Released
- Doing for User Space What We Did for Kernel Space
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