ugh.book

184 Programming

SH(1) Unix Programmer's Manual SH(1)

NAME

sh, for, case, if, while, :, ., break,

continue, cd, eval, exec, exit, export, login,

read, readonly, set, shift, times, trap, umask,

wait - command language

SYNOPSIS

sh [ -ceiknrstuvx ] [ arg ] ...

DESCRIPTION

Sh is a command programming language that

executes commands read from a terminal or a

file. See invocation for the meaning of

arguments to the shell.

[...]

BUGS

If << is used to provide standard input to an

asynchronous process invoked by &, the shell

gets mixed up about naming the input document. A

garbage file /tmp/sh* is created, and the shell

complains about not being able to find the file

by another name.

We spent several minutes trying to understand this BUGS section, but we

couldn’t even figure out what the hell they were talking about. One Unix

expert we showed this to remarked, “As I stared at it and scratched my

head, it occurred to me that in the time it must have taken to track down the

bug and write the BUGS entry, the programmer could have fixed the damn

bug.”

Unfortunately, fixing a bug isn’t enough because they keep coming back

every time there is a new release of the OS. Way back in the early 1980s,

before each of the bugs in Unix had such a large cult following, a

programmer at BBN actually fixed the bug in Berkeley’s make that

requires starting rule lines with tab characters instead of any whitespace. It

wasn’t a hard fix—just a few lines of code.

Like any group of responsible citizens, the hackers at BBN sent the patch

back to Berkeley so the fix could be incorporated into the master Unix

sources. A year later, Berkeley released a new version of Unix with the

make bug still there. The BBN hackers fixed the bug a second time, and

once again sent the patch back to Berkeley.