在许多RFC文档或者代码例子中包含"foo", "bar", "foobar", 今天突然想知道这些词汇的来源以及含义, 在网上搜了一下, 大概明白了一些
http://zh.wikipedia.org/zh/Foobar
在计算机程序设计与计算机技术的相关文档中，术语foobar是一个常见的无名氏化名，常被作为“伪变量”使用。
从技术上讲，“foobar”很可能在1960年代至1970年代初通过迪吉多的系统手册传播开来。另一种说法是，“foobar”可能来源于电子学中反转的foo信号（）；这是因为如果一个数字信号是低电平有效（即负压或零电压代表“1”），那么在信号标记上方一般会标有一根水平横线，而横线的英文即为“bar”。在《新黑客辞典》中，还提到“foo”可能早于“FUBAR”出现。[1]
http://www.catb.org/jargon/html/F/foobar.html
foobar: n.
[very common] Another widely used metasyntactic variable; see foo for etymology. Probably originally propagated through DECsystem manuals by Digital Equipment Corporation (DEC) in 1960s and early 1970s; confirmed sightings there go back to 1972. Hackers do not generally use this to mean FUBAR in either the slang or jargon sense. See also Fred Foobar. In RFC1639, “FOOBAR” was made an abbreviation for “FTP Operation Over Big Address Records”, but this was an obvious backronym. It has been plausibly suggested that “foobar” spread among early computer engineers partly because of FUBAR and partly because “foo bar” parses in electronics techspeak as an inverted foo signal; if a digital signal is active low (so a negative or zero-voltage condition represents a "1") then a horizontal bar is commonly placed over the signal label.
