busybox

History

Denys Vlasenko 350e686f3b ash: [PARSER] Recognise here-doc delimiters terminated by EOF Upstream commit 1: Date: Wed, 26 Sep 2007 17:14:16 +0800 [PARSER] Recognise here-doc delimiters terminated by EOF Previously dash required a <newline> character to be present in order for a here-document delimiter to be detected. Allowing EOF in the absence of a <newline> to play the same purpose allows some intuitive scripts to succeed. POSIX seems to be silence on this so this should be OK. Test case: eval 'cat <<- NOT test NOT' echo OK Old result: test NOTOK New result: test OK Upstream commit 2: Date: Sat, 20 Oct 2007 18:49:31 +0800 [PARSER] Fix here-doc corruption The change [PARSER] Recognise here-doc delimiters terminated by EOF introduced a regerssion whereby lines starting with eofmark but are not equal to eofmark would be corrupted. This patch fixes it. Test case: cat << _ACEOF _ASBOX _ACEOF Old result: SASBOX New result: _ASBOX Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>		2016-10-26 16:26:45 +02:00
..
ash_test	ash: [PARSER] Recognise here-doc delimiters terminated by EOF	2016-10-26 16:26:45 +02:00
hush_test	ash: [PARSER] Recognise here-doc delimiters terminated by EOF	2016-10-26 16:26:45 +02:00
ash_doc.txt
ash_ptr_hack.c	*: make GNU licensing statement forms more regular	2010-08-16 20:14:46 +02:00
ash.c	ash: [PARSER] Recognise here-doc delimiters terminated by EOF	2016-10-26 16:26:45 +02:00
brace.txt
Config.src	config: disentangle PREFER_APPLETS from SH_STANDALONE and SH_NOFORK	2016-07-22 18:48:38 +02:00
cttyhack.c	cttyhack: handle multiple consoles found in sysfs	2012-02-04 21:55:01 +01:00
hush_doc.txt
hush_leaktool.sh
hush.c	ash,hush: set exit code 127 in "sh /does/not/exist" case	2016-10-25 17:00:13 +02:00
Kbuild.src	*: make GNU licensing statement forms more regular	2010-08-16 20:14:46 +02:00
match.c	shell/match.c: shrink by dropping double bool inversion	2010-09-12 15:06:42 +02:00
match.h	hush: optimize #[#] and %[%] for speed. size -2 bytes.	2010-09-04 21:21:07 +02:00
math.c	typo fix in comment	2014-11-20 01:43:30 +01:00
math.h	move endofname() to libbb	2013-02-26 00:36:53 +01:00
random.c	ash,hush: fix a thinko about 2^64-1 factorization	2014-03-15 09:25:46 +01:00
random.h	ash,hush: improve randomness of $RANDOM, add easy-ish way to test it	2014-03-13 12:52:43 +01:00
README
README.job
shell_common.c	ash: [VAR] Initialise OPTIND after importing environment	2016-09-30 14:46:41 +02:00
shell_common.h	ash: [VAR] Initialise OPTIND after importing environment	2016-09-30 14:46:41 +02:00

README

http://www.opengroup.org/onlinepubs/9699919799/
Open Group Base Specifications Issue 7


http://www.opengroup.org/onlinepubs/9699919799/utilities/V3_chap01.html
Shell & Utilities

It says that any of the standard utilities may be implemented
as a regular shell built-in. It gives a list of utilities which
are usually implemented that way (and some of them can only
be implemented as built-ins, like "alias"):

alias
bg
cd
command
false
fc
fg
getopts
jobs
kill
newgrp
pwd
read
true
umask
unalias
wait


http://www.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html
Shell Command Language

It says that shell must implement special built-ins. Special built-ins
differ from regular ones by the fact that variable assignments
done on special builtin are *PRESERVED*. That is,

VAR=VAL special_builtin; echo $VAR

should print VAL.

(Another distinction is that an error in special built-in should
abort the shell, but this is not such a critical difference,
and moreover, at least bash's "set" does not follow this rule,
which is even codified in autoconf configure logic now...)

List of special builtins:

. file
: [argument...]
break [n]
continue [n]
eval [argument...]
exec [command [argument...]]
exit [n]
export name[=word]...
export -p
readonly name[=word]...
readonly -p
return [n]
set [-abCefhmnuvx] [-o option] [argument...]
set [+abCefhmnuvx] [+o option] [argument...]
set -- [argument...]
set -o
set +o
shift [n]
times
trap n [condition...]
trap [action condition...]
unset [-fv] name...

In practice, no one uses this obscure feature - none of these builtins
gives any special reasons to play such dirty tricks.

However. This section also says that *function invocation* should act
similar to special built-in. That is, variable assignments
done on function invocation should be preserved after function invocation.

This is significant: it is not unthinkable to want to run a function
with some variables set to special values. But because of the above,
it does not work: variable will "leak" out of the function.