To do simple locking in shell scripts, you need an atomic system callthat fails if the target already exists, and that is directly exposedin a utility program. Ignoring for a moment what System V did to ln , there are two good candidates on modern Unix systems: link(2) and mkdir(2) .

Mkdir is actually the better of the two (because you don't have tofiddle around with temporary files), but ln is the more common one,probably for two reasons:

1. with

In Java in The Land of Make Believe ,Ryan Tomayko unloads a righteous rant about why Java's license mattersand what effects it has in the Linux and *BSD worlds, with greatbits like:

If you want to get on the bad side of software developers and systemadmins, the fastest route is to waste their time .

Amen. What he said .

(The good news is that Sun GPL'ing Java may finally be changing all ofthis mess, which Tomayko happily acknowledges.)

(From many

Every time I see a mail from a C/R system, I get more and more temptedto teach our mail filtering infrastructure about the most common ones,so that it can automatically acknowledge the challenges, discard themessages, and not bother the users with them at all.

Will this acknowledge a lot of spam, and thus dump it on the peopleoperating those C/R systems? Sure, but that's not our problem. AndI'd clearly be doing our users a service, especially if

This week, we:

• got 15,405 messages from 262 different IP addresses.
• handled 23,822 sessions from 1,467 different IP addresses.
• received 258,033 connections from at least 76,977 different IPaddresses.
• hit a highwater of 7 connections being checked at once.

The overall volume is about the same as last week ; technically it's up a bit, but I figure it'swithin the normal

On V7, UCB BSD 4.x, SunOS 2.x, 3.x and 4.x, the *BSDs, Linux, andanything using GNU fileutils:

; touch a b; ln a b && echo oopsln: b: File exists

On System V, including Solaris 8:

; touch a b; ln a b && echo oopsoops

That's right: the System V version of ln goes to significantextra work over just calling link(2) , and in

The danger of validating XHTML is that the validation is almostcertainly not doing what you believe it's doing.

The problem is that all the common online validators ignore the HTTPContent-Type of what your web server returns when validating your page,and use only the DOCTYPE. This is completely wrong in the case of XHTML,because browsers only treat pages as XHTML if they are served as application/xhtml+xml . All the DOCTYPE does is let the browser decidewhat sort of XHTML it has, since there

Right now, thin clients are doomed for the same reason that they've beendoomed before: users want too much. I believe that watching YouTubevideos and plugging in their USB keys are pretty much the minimum levelof features that users will expect and accept; if they can't do both,they're operating in a fundamentally crippled computing environment,which is not the way to make them happy. And unhappy users sooner orlater push back.

(YouTube is not merely desirable by itself, it'

We've recently been having a problem where one specific clientexperiences really slow IO to one specific NFS mounted filesystem,especially for things like file creation. (Other clients can use thefilesystem at full speed, and this client can use other filesystems atfull speed.)

We immediately thought 'per-filesystem concurrency limits'and soon turned up the Solaris 8 NFS kernel tunable nfs3_max_threads , which the fine documentation helpfullydescribes as:

This symbol controls the maximum number of async threads started perfile

One of the few things that keeps me running while I am only ondialup is ' yum localupdate '. With a combination of' yum check-update ' and ' yum localupdate ' I can get a list ofwhat RPMs I need to update, pull down copies of those RPMs atwork, dump them onto a USB key ,take them home, and then update them locally.

In theory.

In practice, ' yum localupdate ' seems to sometimes ignore RPMsthat I've supplied on the command line if