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Unix+clones Using the GNU Privacy Guard
Post date: April 15, 2005, 20:04 Category: Software Views: 38
Tutorial quote: Tonight we will investigate the gnupg utility (version 1.07). I will be running it on an OpenBSD 3.2 system but, as usual, any unix-like system should not display any significant differences. I will assume that GPG is already installed.

The GNU Privacy Guard can be regarded as a complete replacement for the popular PGP (Pretty Good Privacy) software. The difference between the two is that GnuPG does not have any licensing restrictions and it also runs on more platforms. They are both open source products. Although owned by a commercial entity, a freeware version of PGP is available (although only for Windows and Macintosh).

In a nutshell, what all this software does is allow two parties to communicate securely. This implies the following:
- the message has arrived at its destination unaltered
- the message can only be read by its intended recipient
- the authenticity of the sender has been verified by the recipient
Unix+clones Remote backup using ssh, tar and cron
Post date: April 12, 2005, 21:04 Category: Miscellaneous Views: 51
Tutorial quote: Are you looking for a solution to backup your data to a remote location? While a solid backup solution such as Arkeia or TSM from IBM are nice from an enterprise point of view, simpler solutions are available from a home user's perspective. I will walk you through on you how you can backup your data to a remote server, using the default tools available on all linux systems. In a nutshell, we will use ssh capabilities to allow a cron job to transfer a tarball from you local machine to a remote machine.

For the purpose of this tutorial, the local machine will be called “localmachine” (running slackware) and the remote server will be called “remoteserver” (slackware as well). The user will be joe (me). You will have to substitute those 3 with your own machines names and user.
Ubuntu SAMBA (Domaincontroller) Server For Small Workgroups With Ubuntu 5.10 "Breezy Badger"
Post date: December 14, 2005, 14:12 Category: Network Views: 148
Tutorial quote: This is a detailed description about the steps to set up a Ubuntu based server (Ubuntu 5.10 - Breezy Badger) to act as file- and print server for Windows (tm) workstations in small workgroups. This howto uses the tdb backend for SAMBA to store passwords and account information. This is suitable for workgroups for up to 250 users and is easier to setup than an LDAP backend. A second howto covering the installation of LDAP + SAMBA will be published soon.
Debian ACL(Access Control List) Configuration
Post date: April 4, 2006, 16:04 Category: Installing Views: 21
Tutorial quote: Access Control Lists (ACLs) provide a much more flexible way of specifying permissions on a file or other object than the standard Unix user/group/owner system. Windows NT and above, when running on an NTFS partition, use ACLs to specify permissions on files and directories. This document attempts to show how you can enable ACL support on your Linux box and use Samba to provide an SMB file server for use by machines in a Windows 2000 domain.

ACLs are best stored in the actual file system itself. To that end, there are patches available for ext2 and ext3 that enable ACL support using Extended Attributes (EAs). SGI's XFS also has ACL support built in, but XFS is not currently covered in this document.
Ubuntu Windows to Ubuntu Transition Guide
Post date: April 8, 2006, 11:04 Category: Miscellaneous Views: 84
Tutorial quote: Alright, so you have successfully installed Ubuntu Linux, but now what do you do with it? You are in the right place. I am going to get you started with a guide on how to use your new Ubuntu system. This transition guide is targeted at existing Windows users and will show you how to do program installations, a little system configuration, but primarily highlight some Windows "replacement" programs for common applications you can't live without. This guide's intent is to introduce you to equivalent programs to what you are accustomed to and, hopefully, to cover a good amount of what you might want in a new install. I am basing the content on what I have personally experienced, email feedback from my installation article, questions from the PC Mech Forums, and common topics from the Ubuntu Forums. Hopefully this will answer a lot of questions you may have before you ever have them.
Unix+clones SpamAssassin, ClamAV and Procmail Howto
Post date: April 15, 2005, 20:04 Category: Network Views: 44
Tutorial quote: This document describes how to install SpamAssassin (for filtering SPAM) and ClamAV (for filtering viruses, trojans, worms, etc.) and how to invoke them by using procmail recipes. It is suitable for scenarios where Sendmail or Postfix deliver emails to local users. It should work (maybe with slight changes concerning paths etc.) on all *nix operating systems. I tested it on Debian Woody so far.

In the end you will have a system where Sendmail or Postfix deliver emails to a local user; the emails are passed to procmail which invokes SpamAssassin and ClamAV in order to filter the emails before they arrive in the user's inbox. However, the installation of Sendmail and Postfix are not covered in this document.

This howto is meant as a practical guide.
Unix+clones Get More Out of Your Pipe with Apache and mod_gzip
Post date: April 14, 2005, 09:04 Category: Network Views: 41
Tutorial quote: Some Web sites seem like they are designed to annoy and alienate visitors. Teeny tiny fixed fonts, weirdo fixed page widths, ad servers on Mars, and the content won't load until the ads do, and all kinds of dynamic jiggery-pokery that does everything but quickly deliver a nice, readable page.

Webmasters who are serious about running high-performance Web servers, and who want pleased and delighted visitors, have a great tool in Apache 1.3's mod_gzip. mod_gzip compresses pages on the fly, reducing their size considerably. Depending on the types of files served, you'll see size reductions ranging from 20%- 80%, and a nice increase in server efficiency. Nothing is needed on the client side, except sane modern Web browsers like Mozilla, Firefox, Opera, Galeon, and Konqueror. Mozilla, Firefox, and Opera are nice cross-platform browsers with all kinds of neat features, so don't be afraid to standardize on one of them.
RedHat Choosing an I/O Scheduler for Red Hat Enterprise Linux 4
Post date: July 18, 2005, 18:07 Category: Benchmarks Views: 176
Tutorial quote: The Linux kernel, the core of the operating system, is responsible for controlling disk access by using kernel I/O scheduling. Red Hat Enterprise Linux 3 with a 2.4 kernel base uses a single, robust, general purpose I/O elevator. The 2.4 I/O scheduler has a reasonable number of tuning options by controlling the amount of time a request remains in an I/O queue before being serviced using the elvtune command. While Red Hat Enterprise Linux 3 offers most workloads excellent performance, it does not always provide the best I/O characteristics for the wide range of applications in use by Linux users these days. The I/O schedulers provided in Red Hat Enterprise Linux 4, embedded in the 2.6 kernel, have advanced the I/O capabilities of Linux significantly. With Red Hat Enterprise Linux 4, applications can now optimize the kernel I/O at boot time, by selecting one of four different I/O schedulers.
Linux Sawing Linux Logs with Simple Tools
Post date: April 14, 2005, 08:04 Category: Security Views: 37
Tutorial quote: So there you are with all of your Linux servers humming along happily. You have tested, tweaked, and configured until they are performing at their peak of perfection. Users are hardly whining at all. Life is good. You may relax and indulge in some nice, relaxing rounds of TuxKart. After all, you earned it.

Except for one little remaining chore: monitoring your log files. [insert horrible alarming music of your choice here.] You're conscientious, so you know you can't just ignore the logs until there's a problem, especially for public services like Web and mail. Somewhere up in the pointy-haired suites, they may even be plotting to require you to track and analyze all sorts of server statistics.

Not to worry, for there are many ways to implement data reduction, which is what log parsing is all about. You want to slice and dice your logs to present only the data you're interested in viewing. Unless you wish to devote your entire life to manually analyzing log files. Even if you only pay attention to logfiles when you're debugging a problem, having some tools to weed out the noise is helpful.
Linux Creating Really Teensy ELF Executables for Linux
Post date: April 12, 2005, 14:04 Category: Miscellaneous Views: 34
Tutorial quote: If you're a programmer who's become fed up with software bloat, then may you find herein the perfect antidote.

This document explores methods for squeezing excess bytes out of simple programs. (Of course, the more practical purpose of this document is to describe a few of the inner workings of the ELF file format and the Linux operating system. But hopefully you can also learn something about how to make really teensy ELF executables in the process.)

Please note that the information and examples given here are, for the most part, specific to ELF executables on a Linux platform running under an Intel-386 architecture. I imagine that a good bit of the information is applicable to other ELF-based Unices, but my experiences with such are too limited for me to say with certainty.

The assembly code that appears in this document is written for use with Nasm. (Besides being more appropriate for our needs, Nasm's syntax beats the hell out of AT&T syntax for anyone who learned x86 assembly language before learning to use Gas.) Nasm is freely available and extremely portable; see http://nasm.sourceforge.net/.

Please also note that if you aren't a little bit familiar with assembly code, you may find parts of this document sort of hard to follow.