1        Logging and backgrounding
   3By default, bb_[p]error_msg[_and_die] messages go to stderr,
   4and of course, usually applets do not auto-background. :)
   6Historically, daemons and inetd services are different.
   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.
  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.
  20To help with that, busybox applets should have options to override
  21default behavior, whatever that is for a given applet.
  24Current situation is a bit of a mess:
  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    behaviour can be overridden with experimental LOGGING env.var
  49    (can be set to either "none" or "syslog")
  51Total: 13 applets (+1 obsolete),
  52 4 log to syslog by default (crond fakeidentd inetd zcip),
  53 5 never log to syslog (acpid httpd telnetd klogd syslogd, last two
  54 - for obviously correct reasons),
  55 there are no daemons which always log to syslog,
  56 12 auto-background if not run as inetd services (all except dnsd.
  57 Note that there is no "standard" dnsd AFAIKS). But see below
  58 for daemons (tcpsvd etc) which don't auto-background.
  60miscutils/crond.c:            logmode = LOGMODE_SYSLOG;
  61networking/dnsd.c:            logmode = LOGMODE_SYSLOG;
  62networking/ftpd.c:            logmode = LOGMODE_NONE;
  63networking/ftpd.c:            logmode |= LOGMODE_SYSLOG;
  64networking/inetd.c:           logmode = LOGMODE_SYSLOG;
  65networking/isrv_identd.c:     logmode = LOGMODE_SYSLOG;
  66networking/telnetd.c:         logmode = LOGMODE_SYSLOG;
  67networking/udhcp/dhcpc.c:     logmode = LOGMODE_NONE;
  68networking/udhcp/dhcpc.c:     logmode |= LOGMODE_SYSLOG;
  69networking/udhcp/dhcpc.c:     logmode &= ~LOGMODE_STDIO;
  70networking/udhcp/dhcpd.c:     logmode = LOGMODE_NONE;
  71networking/udhcp/dhcpd.c:     logmode |= LOGMODE_SYSLOG;
  72networking/zcip.c:            logmode |= LOGMODE_SYSLOG;
  75These daemons never auto-background and never log to syslog:
  77lpd - inetd service. Has nothing to log so far, though
  78dhcprelay - standard behavior
  79inotifyd - standard behavior
  80runsv - standard behavior
  81runsvdir - standard behavior
  82svlogd - standard behavior
  83tcpsvd, udpsvd - standard behavior
  84tftpd - standard behavior
  87Non-daemons (seems to be use syslog for a good reason):
  89networking/nameif.c:          logmode |= LOGMODE_SYSLOG;
  90loginutils/chpasswd.c:        logmode = LOGMODE_BOTH;
  91loginutils/chpasswd.c:        logmode = LOGMODE_STDIO;
  92loginutils/getty.c:           logmode = LOGMODE_BOTH;
  93loginutils/getty.c:           logmode = LOGMODE_NONE;
  94loginutils/passwd.c:          logmode = LOGMODE_STDIO;
  95loginutils/passwd.c:          logmode = LOGMODE_BOTH;
  96loginutils/sulogin.c:         logmode = LOGMODE_SYSLOG; (used if stdio isn't a tty)
  97loginutils/sulogin.c:         logmode = LOGMODE_BOTH;
  98util-linux/mount.c:           logmode = LOGMODE_SYSLOG; (used in a backgrounded NFS mount helper)