busybox

History

Eicke Herbertz 1b30c63dfd shell: also do word splitting when -d DELIM is used The original commit `3bef5d89b0` introduced an additional check for an unset `opt_d` before doing word splitting. I'm unsure why it's there in the first place, but the commit message also describes a different behaviour than what -d actually does in bash, while the code mostly does the right thing. `opt_d` sets the line delimiter for read to stop reading and should not affect word splitting. Testcase: $ echo qwe rty \| { read -d Z a b; echo a:$a b:$b; } a:qwe b:rty function old new delta shell_builtin_read 1314 1304 -10 Signed-off-by: Eicke Herbertz <wolletd@posteo.de> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>		2021-06-05 18:06:47 +02:00
..
ash_test	ash: match bash behavior for ${empty_var/*/repl}	2021-01-09 08:46:54 +01:00
hush_test	typo fix	2020-12-25 19:08:16 +01:00
ash_doc.txt
ash_ptr_hack.c
ash.c	ash: placate -Werror=format-security	2021-02-18 13:45:49 +01:00
brace.txt
Config.src	nologin: make it possible to build it as single applet	2020-06-24 15:05:22 +02:00
cttyhack.c	config: update size information	2018-12-28 03:20:17 +01:00
hush_doc.txt
hush_leaktool.sh
hush.c	hush: beautify ^D handling to match ash / bash	2021-04-13 16:42:17 +02:00
Kbuild.src
match.c
match.h
math.c	shell: remove FAST_FUNC from a static function	2020-10-01 00:57:05 +02:00
math.h	shell: move all definitions of strto_arith_t() together	2019-05-26 14:02:10 +02:00
random.c
random.h
README
README.job
shell_common.c	shell: also do word splitting when -d DELIM is used	2021-06-05 18:06:47 +02:00
shell_common.h	hush: fix "export PS1=xyz" and "local PS1=xyz" messing up prompt	2019-05-14 18:56:04 +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.