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Senior System Administrator
Jan Schaumann is a New Yorker in exile, lured to the US West Coast by the world's largest and most popular website: as a Senior System Administrator at Yahoo!, he now helps to maintain literally thousands of servers in dozens of rather large datacenters in virtually all timezones around the globe. He continually discovers new and exciting ways in which a unix system can fail. Jan holds both a BS and MS in Computer Science from Stevens Institute of Technology. He joined the NetBSD Project as a developer in 2002, working in a variety of areas. In his non-geek life, Jan enjoys surfing, snowboarding and skateboarding. Together with his wife, he lives in San Francisco. For now.
AbstractBack in the day when dinosaurs roamed the earth and you could measure how good your System Administrator was by how much time he was able to spend on Usenet, Randal L. Schwartz used to hand out the ``Useless Use of Cat'' awards, reminding people not to waste expensive fork-exec's when the shell could do the work itself. Time has passed, Usenet is still a strange place, yet shell programmers continue to waste scarce resources by building long pipelines of unix commands.
In this presentation, we will:
- show how seemingly simple pipelines destroy performance once one has to run the task on thousands of servers dozens of times a day
- show examples of useless use of: cat, case, grep, head, ls, sed, tail, ... (all examples were found in real-live production programs)
- show when _not_ to optimize
- demonstrate good use of shell programming style and test harnesses