source: MondoRescue/branches/2.2.5/mindi-busybox/shell/README @ 1765

Last change on this file since 1765 was 1765, checked in by Bruno Cornec, 12 years ago

Update to busybox 1.7.2

File size: 3.8 KB
Line 
1Various bits of what is known about busybox shells, in no particular order.
2
32007-06-13
4hush: exec <"$1" doesn't do parameter subst
5
62007-05-24
7hush: environment-related memory leak plugged, with net code size
8decrease.
9
102007-05-24
11hush: '( echo ${name )' will show syntax error message, but prompt
12doesn't return (need to press <enter>). Pressing Ctrl-C, <enter>,
13'( echo ${name )' again, Ctrl-C segfaults.
14
152007-05-21
16hush: environment cannot be handled by libc routines as they are leaky
17(by API design and thus unfixable): hush will leak memory in this script,
18bash does not:
19pid=$$
20while true; do
21    unset t;
22    t=111111111111111111111111111111111111111111111111111111111111111111111111
23    export t
24    ps -o vsz,pid,comm | grep " $pid "
25done
26The fix is to not use setenv/putenv/unsetenv but manipulate env ourself. TODO.
27hush: meanwhile, first three command subst bugs mentioned below are fixed. :)
28
292007-05-06
30hush: more bugs spotted. Comparison with bash:
31bash-3.2# echo "TEST`date;echo;echo`BEST"
32TESTSun May  6 09:21:05 CEST 2007BEST         [we dont strip eols]
33bash-3.2# echo "TEST`echo '$(echo ZZ)'`BEST"
34TEST$(echo ZZ)BEST                            [we execute inner echo]
35bash-3.2# echo "TEST`echo "'"`BEST"
36TEST'BEST                                     [we totally mess up this one]
37bash-3.2# echo `sleep 5`
38[Ctrl-C should work, Ctrl-Z should do nothing][we totally mess up this one]
39bash-3.2# if true; then
40> [Ctrl-C]
41bash-3.2#                                     [we re-issue "> "]
42bash-3.2# if echo `sleep 5`; then
43> true; fi                                    [we execute sleep before "> "]
44
452007-05-04
46hush: made ctrl-Z/C work correctly for "while true; do true; done"
47(namely, it backgrounds/interrupts entire "while")
48
492007-05-03
50hush: new bug spotted: Ctrl-C on "while true; do true; done" doesn't
51work right:
52# while true; do true; done
53[1] 0 true <-- pressing Ctrl-C several times...
54[2] 0 true
55[3] 0 true
56Segmentation fault
57
582007-05-03
59hush: update on "sleep 1 | exit 3; echo $?" bug.
60parse_stream_outer() repeatedly calls parse_stream().
61parse_stream() is now fixed to stop on ';' in this example,
62fixing it (parse_stream_outer() will call parse_stream() 1st time,
63execute the parse tree, call parse_stream() 2nd time and execute the tree).
64But it's not the end of story.
65In more complex situations we _must_ parse way farther before executing.
66Example #2: "{ sleep 1 | exit 3; echo $?; ...few_lines... } >file".
67Because of redirection, we cannot execute 1st pipe before we parse it all.
68We probably need to learn to store $var expressions in parse tree.
69Debug printing of parse tree would be nice too.
70
712007-04-28
72hush: Ctrl-C and Ctrl-Z for single NOFORK commands are working.
73Memory and other resource leaks (opendir) are not addressed
74(testcase is "rm -i" interrupted by ctrl-c).
75
762007-04-21
77hush: "sleep 5 | sleep 6" + Ctrl-Z + fg seems to work.
78"rm -i" + Ctrl-C, "sleep 5" + Ctrl-Z still doesn't work
79for SH_STANDALONE case :(
80
812007-04-21
82hush: fixed non-backgrounding of "sleep 1 &" and totally broken
83"sleep 1 | sleep 2 &". Noticed a bug where successive jobs
84get numbers 1,2,3 even when job #1 has exited before job# 2 is started.
85(bash reuses #1 in this case)
86
872007-04-21
88hush: "sleep 1 | exit 3; echo $?" prints 0 because $? is substituted
89_before_ pipe gets executed!! run_list_real() already has "pipe;echo"
90parsed and handed to it for execution, so it sees "pipe"; "echo 0".
91
922007-04-21
93hush: removed setsid() and made job control sort-of-sometimes-work.
94Ctrl-C in "rm -i" works now except for SH_STANDALONE case.
95"sleep 1 | exit 3" + "echo $?" works, "sleep 1 | exit 3; echo $?"
96shows exitcode 0 (should be 3). "sleep 1 | sleep 2 &" fails horribly.
97
982007-04-14
99lash, hush: both do setsid() and as a result don't have ctty!
100Ctrl-C doesn't work for any child (try rm -i), etc...
101lash: bare ">file" doesn't create a file (hush works)
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