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Diffstat (limited to 'release/src/router/busybox/docs/logging_and_backgrounding.txt')
| -rw-r--r-- | release/src/router/busybox/docs/logging_and_backgrounding.txt | 96 |
1 files changed, 96 insertions, 0 deletions
diff --git a/release/src/router/busybox/docs/logging_and_backgrounding.txt b/release/src/router/busybox/docs/logging_and_backgrounding.txt new file mode 100644 index 00000000..62a6d155 --- /dev/null +++ b/release/src/router/busybox/docs/logging_and_backgrounding.txt @@ -0,0 +1,96 @@ + Logging and backgrounding + +By default, bb_[p]error_msg[_and_die] messages go to stderr, +and of course, usually applets do not auto-background. :) + +Historically, daemons and inetd services are different. + +Busybox is trying to provide compatible behavior, thus if an applet +is emulating an existing utility, it should mimic it. If utility +auto-backgrounds itself, busybox applet should do the same. +If utility normally logs to syslog, busybox applet should do +the same too. + +However, busybox should not needlessly restrict the freedom +of the users. And users have different needs and different preferences. +Some might like logging everything from daemons to syslog. +Others prefer running stuff under runsv/svlogd and thus would like +logging to stderr and no daemonization. + +To help with that, busybox applets should have options to override +default behavior, whatever that is for a given applet. + + +Current sutiation is a bit of a mess: + +acpid - auto-backgrounds unless -d +crond - auto-backgrounds unless -f, logs to syslog unless -d or -L. + option -d logs to stderr, -L FILE logs to FILE +devfsd - (obsolete) +dnsd - option -d makes it background and log to syslog +fakeidentd - inetd service. Auto-backgrounds and logs to syslog + if no -f and no -i and no -w (-i is "inetd service" flag, + -w is "inetd-wait service" flag) +ftpd - inetd service. Logs to syslog with -S, with -v logs to strerr too +httpd - auto-backgrounds unless -f or -i (-i is "inetd service" flag) +inetd - auto-backgrounds unless -f, logs to syslog unless -e +klogd - auto-backgrounds unless -n +syslogd - auto-backgrounds unless -n +telnetd - auto-backgrounds unless -f or -i (-i is "inetd service" flag) +udhcpc - auto-backgrounds unless -f after lease is obtained, + option -b makes it background sooner (when lease attempt + fails and retries start), + after backgrounding it stops logging to stderr; + logs to stderr, but option -S makes it log *also* to syslog +udhcpd - auto-backgrounds and do not log to stderr unless -f, + otherwise logs to stderr, but option -S makes it log *also* to syslog +zcip - auto-backgrounds and logs *also* to syslog unless -f + +Total: 13 applets (+1 obsolete), + 4 log to syslog by default (crond fakeidentd inetd zcip), + 5 never log to syslog (acpid httpd telnetd klogd syslogd, last two + - for obviously correct reasons), + there are no daemons which always log to syslog, + 12 auto-background if not run as inetd servies (all except dnsd. + Note that there is no "standard" dnsd AFAIKS). But see below + for daemons (tcpsvd etc) which don't auto-background. + +miscutils/crond.c: logmode = LOGMODE_SYSLOG; +networking/dnsd.c: logmode = LOGMODE_SYSLOG; +networking/ftpd.c: logmode = LOGMODE_NONE; +networking/ftpd.c: logmode |= LOGMODE_SYSLOG; +networking/inetd.c: logmode = LOGMODE_SYSLOG; +networking/isrv_identd.c: logmode = LOGMODE_SYSLOG; +networking/telnetd.c: logmode = LOGMODE_SYSLOG; +networking/udhcp/dhcpc.c: logmode = LOGMODE_NONE; +networking/udhcp/dhcpc.c: logmode |= LOGMODE_SYSLOG; +networking/udhcp/dhcpc.c: logmode &= ~LOGMODE_STDIO; +networking/udhcp/dhcpd.c: logmode = LOGMODE_NONE; +networking/udhcp/dhcpd.c: logmode |= LOGMODE_SYSLOG; +networking/zcip.c: logmode |= LOGMODE_SYSLOG; + + +These daemons never auto-background and never log to syslog: + +lpd - inetd service. Has nothing to log so far, though +dhcprelay - standard behavior +inotifyd - standard behavior +runsv - standard behavior +runsvdir - standard behavior +svlogd - standard behavior +tcpsvd, udpsvd - standard behavior +tftpd - standard behavior + + +Non-daemons (seems to be use syslog for a good reason): + +networking/nameif.c: logmode |= LOGMODE_SYSLOG; +loginutils/chpasswd.c: logmode = LOGMODE_BOTH; +loginutils/chpasswd.c: logmode = LOGMODE_STDIO; +loginutils/getty.c: logmode = LOGMODE_BOTH; +loginutils/getty.c: logmode = LOGMODE_NONE; +loginutils/passwd.c: logmode = LOGMODE_STDIO; +loginutils/passwd.c: logmode = LOGMODE_BOTH; +loginutils/sulogin.c: logmode = LOGMODE_SYSLOG; (used if stdio isn't a tty) +loginutils/sulogin.c: logmode = LOGMODE_BOTH; +util-linux/mount.c: logmode = LOGMODE_SYSLOG; (used in a backgrounded NFS mount helper) |