source: branches/2.2.9/mindi-busybox/docs/logging_and_backgrounding.txt @ 3320

Last change on this file since 3320 was 3320, checked in by Bruno Cornec, 5 years ago
  • Re-add (thanks git BTW) the 2.2.9 branch which had been destroyed in the move to 3.0
  • Property svn:eol-style set to native
File size: 4.2 KB
Line 
1    Logging and backgrounding
2
3By default, bb_[p]error_msg[_and_die] messages go to stderr,
4and of course, usually applets do not auto-background. :)
5
6Historically, daemons and inetd services are different.
7
8Busybox is trying to provide compatible behavior, thus if an applet
9is emulating an existing utility, it should mimic it. If utility
10auto-backgrounds itself, busybox applet should do the same.
11If utility normally logs to syslog, busybox applet should do
12the same too.
13
14However, busybox should not needlessly restrict the freedom
15of the users. And users have different needs and different preferences.
16Some might like logging everything from daemons to syslog.
17Others prefer running stuff under runsv/svlogd and thus would like
18logging to stderr and no daemonization.
19
20To help with that, busybox applets should have options to override
21default behavior, whatever that is for a given applet.
22
23
24Current situation is a bit of a mess:
25
26acpid - auto-backgrounds unless -d
27crond - auto-backgrounds unless -f, logs to syslog unless -d or -L.
28    option -d logs to stderr, -L FILE logs to FILE
29devfsd - (obsolete)
30dnsd - option -d makes it background and log to syslog
31fakeidentd - inetd service. Auto-backgrounds and logs to syslog
32    if no -f and no -i and no -w (-i is "inetd service" flag,
33    -w is "inetd-wait service" flag)
34ftpd - inetd service. Logs to syslog with -S, with -v logs to strerr too
35httpd - auto-backgrounds unless -f or -i (-i is "inetd service" flag)
36inetd - auto-backgrounds unless -f, logs to syslog unless -e
37klogd - auto-backgrounds unless -n
38syslogd - auto-backgrounds unless -n
39telnetd - auto-backgrounds unless -f or -i (-i is "inetd service" flag)
40udhcpc - auto-backgrounds unless -f after lease is obtained,
41    option -b makes it background sooner (when lease attempt
42    fails and retries start),
43    after backgrounding it stops logging to stderr;
44    logs to stderr, but option -S makes it log *also* to syslog
45udhcpd - auto-backgrounds and do not log to stderr unless -f,
46    otherwise logs to stderr, but option -S makes it log *also* to syslog
47zcip - auto-backgrounds and logs *also* to syslog unless -f
48
49Total: 13 applets (+1 obsolete),
50 4 log to syslog by default (crond fakeidentd inetd zcip),
51 5 never log to syslog (acpid httpd telnetd klogd syslogd, last two
52 - for obviously correct reasons),
53 there are no daemons which always log to syslog,
54 12 auto-background if not run as inetd services (all except dnsd.
55 Note that there is no "standard" dnsd AFAIKS). But see below
56 for daemons (tcpsvd etc) which don't auto-background.
57
58miscutils/crond.c:            logmode = LOGMODE_SYSLOG;
59networking/dnsd.c:            logmode = LOGMODE_SYSLOG;
60networking/ftpd.c:            logmode = LOGMODE_NONE;
61networking/ftpd.c:            logmode |= LOGMODE_SYSLOG;
62networking/inetd.c:           logmode = LOGMODE_SYSLOG;
63networking/isrv_identd.c:     logmode = LOGMODE_SYSLOG;
64networking/telnetd.c:         logmode = LOGMODE_SYSLOG;
65networking/udhcp/dhcpc.c:     logmode = LOGMODE_NONE;
66networking/udhcp/dhcpc.c:     logmode |= LOGMODE_SYSLOG;
67networking/udhcp/dhcpc.c:     logmode &= ~LOGMODE_STDIO;
68networking/udhcp/dhcpd.c:     logmode = LOGMODE_NONE;
69networking/udhcp/dhcpd.c:     logmode |= LOGMODE_SYSLOG;
70networking/zcip.c:            logmode |= LOGMODE_SYSLOG;
71
72
73These daemons never auto-background and never log to syslog:
74
75lpd - inetd service. Has nothing to log so far, though
76dhcprelay - standard behavior
77inotifyd - standard behavior
78runsv - standard behavior
79runsvdir - standard behavior
80svlogd - standard behavior
81tcpsvd, udpsvd - standard behavior
82tftpd - standard behavior
83
84
85Non-daemons (seems to be use syslog for a good reason):
86
87networking/nameif.c:          logmode |= LOGMODE_SYSLOG;
88loginutils/chpasswd.c:        logmode = LOGMODE_BOTH;
89loginutils/chpasswd.c:        logmode = LOGMODE_STDIO;
90loginutils/getty.c:           logmode = LOGMODE_BOTH;
91loginutils/getty.c:           logmode = LOGMODE_NONE;
92loginutils/passwd.c:          logmode = LOGMODE_STDIO;
93loginutils/passwd.c:          logmode = LOGMODE_BOTH;
94loginutils/sulogin.c:         logmode = LOGMODE_SYSLOG; (used if stdio isn't a tty)
95loginutils/sulogin.c:         logmode = LOGMODE_BOTH;
96util-linux/mount.c:           logmode = LOGMODE_SYSLOG; (used in a backgrounded NFS mount helper)
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