Perl: The Write-Only Language That Built the Early Web
Larry Wall created Perl in 1987 as a glue language for Unix system administration, drawing inspiration from C, sed, awk, shell, and what appears to have been a thesaurus dropped into a blender. Perl's motto — "there's more than one way to do it" — is either liberating or terrifying...
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PHP: The Accidental Language That Runs Half the Internet
Rasmus Lerdorf created PHP in 1994 as a small set of Perl scripts to track visits to his online CV. He called it "Personal Home Page Tools," had no intention of building a programming language, and has spent much of the subsequent thirty years being diplomatically candid about this. PHP...
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The Sticky Bit: A Permission Flag That No Longer Does What It Was Invented For
Unix's sticky bit (chmod +t) was introduced in early Unix to tell the kernel to keep a program's text segment in swap space after execution — making frequently-used binaries load faster on slow hardware. By the time hardware made this irrelevant, the sticky bit had acquired a second, entirely unrelated...
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core dump: Your Program’s Farewell Letter
When a Unix process crashes badly enough — segfault, illegal instruction, unhandled signal — the kernel writes a snapshot of the process's entire memory to disk: a core dump. The name comes from magnetic core memory, the dominant RAM technology of the 1950s and 1960s, making "core dump" yet another...
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LD_PRELOAD: The Legitimate Backdoor Built Into Every Linux System
LD_PRELOAD is an environment variable that tells the dynamic linker to load a specified shared library before all others — including the C standard library — giving it first pick of every function call the program makes. It exists for entirely legitimate reasons: testing, debugging, hot-patching without recompilation. It has...
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The OOM Killer: Linux’s Method of Fixing Memory Problems by Murdering Processes
When a Linux system runs critically low on memory, the kernel doesn't gracefully degrade or politely ask applications to use less RAM. It invokes the Out-Of-Memory killer — a subsystem that scores every running process on a combination of memory usage, runtime, and a dash of inscrutable heuristics, then terminates...
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