Re: How different is one UNIX or LINUX from another?

On Mon, 29 Sep 2008, in the Usenet newsgroup alt.os.linux.suse, in article
<gbq45k$jf5$1@xxxxxxxxxxxxxxxxxxxxxx>, bb wrote:

Artificer wrote:

There are several well known UNIX systems like Solaris, AIX or HP UX
and also many well known Linux Distros like SUSE and RedHat. I wonder
if somebody becomes a good administrator on a Linux Distro if he will
be able to do basic administration of a UNIX system or if somebody is
good administrator of one UNIX System if she will be able to do basic
admin of another UNIX system.

If you are learning the underlying core - rather than the individual
GUI tools that are tailored from a specific UNIX or Linux distribution,
then you've got a good start.

How different are SUSE Linux and Solaris from an administrator point
of view?

How different is chocolate ice-cream from vanilla? They're both
ice cream, but the flavoring is very different. Does that make them
incompatible? Learning to make or eat one won't work on the other?

Each has it's "proprietary" tools - you won't find YAST on other Linux
distributions (never mind on UNIX), just as you won't find SMIT on
anything other than AIX, or SAM on anything but HP-UX. But 'vi' (or
clones like 'vim' or 'nvi') are found on all, just as a Bourne type
shell (either '/bin/sh' itself, or one of many improved versions like
ksh, bash, ash, zsh, and so on) are always there.

There is 2 major differences that may or not may be important.

first, a linux system is adjusted a bit to play well as a non
productive system for a single user, who turn the computer off when
it's not in use. The cron system is reconstructed for that, so jobs
are running when the system is up, while the old unixes has jobs that
only run some nights, and really don't like to be powered off when
the user go to bed.

crond (8) - cron daemon (Dillon's Cron)

cron (8) - daemon to execute scheduled commands (Vixie Cron)

crond (8) - A daemon for time scheduled execution of commands
(ucrond version 1.4.1)

anacron (8) - runs commands periodically

fcron (8) - daemon to execute scheduled tasks

Dillon and Vixie cron are classic cron daemons, that will run jobs at
specific times of day/week/month. If the system is off or in single
user mode (SysV run-level 1), cron is not run, and any tasks scheduled
to run at that time will not run - now, or when the system goes back
to multi-user mode. There is no 'catch-up' mode for these (or the
standard UNIX) cron daemons. 'anacron' only operates in a 'delay after
system start' mode, and will run any/all cron-jobs that haven't been
run in the scheduled (for each task) daily (or greater) interval.
'ucrond' and 'fcron' _can_ be configured to run in the "classic" 'run
at a particular time of day' manner (as Dillon and Vixie cron do), but
they can also be set to operate in a 'delay after system start' mode
like anacron. Thus, the cron behavior depends on which daemon is
installed on your system, and possibly how that daemon is configured.

Second, linux systems are build with gnu software, while other unixes
has their own utils and gnu software on top of it, which you must think
of when you work with them, eg. tar on linux is gtar on unix, or you
get the system default tar that can make a mess of your files.

Ah, you've been bit by that little difference too. And don't forget
the *BSDs which have their own similarities and differences.

But once you are a good admin of linux or unix you know how to read
manuals and figure out how it works.

Someone has pointed out the similarities between *nix administrators
and auto mechanics. While less true today because of the computers
used in cars (and the specialized GUI tools from each manufacturer),
a mechanic trained on Toyotas, Fords or BMWs can work on Hondas,
Chevys or Mercedes a heck of a lot easier than a person who is a
trained plumber or lawyer and knows nothing about motor vehicles.

Old guy
.

Relevant Pages

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