Update documentation

Signed-off-by: David Oberhollenzer <david.oberhollenzer@tele2.at>

5 files changed, 79 insertions, 7 deletions

diff --git a/README.md b/README.md
index c36ea8b..06ba004 100644
--- a/README.md
+++ b/README.md
@@ -2,7 +2,8 @@
 
 This directory contains the source code for a tiny service supervision
 framework devised for the Pygos system, consisting of an init daemon,
-a small syslog daemon and various command line utilities.
+a small syslog daemon, a _definitely_ non standards compliant cron
+implementation and various command line utilities.
 
 The individual parts of the framework are designed to be independent of
 each other (for instance, the tiny syslogd is intended to work with *any*
@@ -62,6 +63,8 @@ services and configuration provided with this package.
 See [docs/usyslogd.md](docs/usyslogd.md) for details on the tiny syslog
 implementation.
 
+See [docs/gcron.md](docs/gcron.md) for details on the cron implementation.
+
 
 ## Why
 
@@ -110,4 +113,3 @@ that have been considered include:
 
     Nice and simple. Probably the best fit if the rest of your user space is
     busybox as well.
-
diff --git a/cmd/service/service.8 b/cmd/service/service.8
index a897817..3ca7cb2 100644
--- a/cmd/service/service.8
+++ b/cmd/service/service.8
@@ -22,7 +22,7 @@ Displays a list of currently enabled services. If an optional target is
 specified, lists services only for this target, otherwise, list services
 for all targets.
 .TP
-.BR enable " " \fI<command>\fP " " \fI[arguments]\fP
+.BR enable " " \fI<service>\fP " " \fI[arguments]\fP
 Enable (but do not start) a system service by creating a symlink in the
 configuration directory, pointing to the service template file.
 
@@ -34,7 +34,7 @@ in the gcrond configuration directory, pointing to the service file.
 
 The extension \fB.gcron\fP is automatically appended to the service name.
 .TP
-.BR disable " " \fI<command>\fP " " \fI[arguments]\fP
+.BR disable " " \fI<service>\fP " " \fI[arguments]\fP
 Disable (but do not stop) a system service by removing the corresponding
 symlink in the configuration directory.
 
@@ -45,7 +45,7 @@ the desired service instance.
 If built with support for gcrond, disable a gcron service by removing the
 corresponding symlink in the gcron configuration directory.
 .TP
-.BR dumpscript " " \fI<command>\fP " " \fI[arguments]\fP
+.BR dumpscript " " \fI<service>\fP " " \fI[arguments]\fP
 Parse a service file from and produce a pseudo shell script containing the
 exact commands executed when starting the service.
 .SH AVAILABILITY
diff --git a/docs/cmdline.md b/docs/cmdline.md
index c3945ec..e1500aa 100644
--- a/docs/cmdline.md
+++ b/docs/cmdline.md
@@ -13,6 +13,10 @@ Currently available service commands are:
  * disable - disable a service. If the service is parameterized, requires the
    same arguments used for enabling, to disable the specific instance of the
    service.
+ * schedule - enable a gcrond service. Only available if this package is built
+   with gcrond.
+ * unschedule - disnable a gcrond service. Only available if this package is
+   built with gcrond.
  * dumpscript - generate an equivalent shell script from the `exec` lines of
    a service after applying all parameter substitutions.
  * list - list all enabled service. A target can be specified to only list
diff --git a/docs/defconfig.md b/docs/defconfig.md
index cdfe333..3ab6563 100644
--- a/docs/defconfig.md
+++ b/docs/defconfig.md
@@ -71,6 +71,12 @@ the `sysinit` target and *before* the `network` target:
  * ifcfg - static network configuration
    Does the static network configuration outlined in [network.md](network.md)
 
+The following services are enabled by default and configured to run *after*
+the `network` target:
+
+ * gcrond - if the `gcrond` daemon is compiled with this package, this service
+   is enabled by default.
+
 
 ## Default Shutdown and Reboot Services
 
@@ -98,8 +104,6 @@ For the shutdown and reboot targets, the following services are executed:
    type service can be enabled to manage an instace of the `hostapd` program.
  * unbound - A respawn type service that manages an instance of the `unbound`
    name resolver.
- * usyslogd - A respawn type service that manages an instance of the `usyslogd`
-   syslogd implementation that is part of this package.
  * hwclock - If the system has a hardware clock, this service can restore the
    kernels clock from the hardware at bootup, between the `vfs` and `sysinit`
    targets.
diff --git a/docs/gcron.md b/docs/gcron.md
new file mode 100644
index 0000000..4327083
--- /dev/null
+++ b/docs/gcron.md
@@ -0,0 +1,62 @@
+# Gcron
+
+Gcron is a small daemon that executes batch commands once a certain
+condition is met.
+
+In a typical installation, it reads configuration files from `/etc/gcron.d`.
+If used together with the init system in this package, the `service` command
+can be used to administer symlinks in that directory, pointing
+to `/usr/share/init/<name>.gcron`.
+
+Each file in the configuration directory represents a single scheduled batch
+job. The syntax and most of the keywords are similar to `initd` service files
+(See [services.md](services.md)).
+
+## Cron Style Patterns
+
+The following keywords can be used to specify classic cron style patterns for
+when a job should be run:
+
+ * `hour`
+ * `minute`
+ * `dayofmonth`
+ * `dayofweek`
+ * `month`
+
+For each of those keywords, a comma separated sequence of times can be
+specified. Time ranges can be specified using the syntax `<start>-<end>`,
+or using `*` for every possible value. A sequence (either range or star)
+can be suffixed with `/<step>` to specify an increment.
+For instance, `minute */5` means every five minutes and `minute 15-30/2`
+means every two minutes between quarter past and half past.
+
+In addition to numeric values, the keywords `dayofweek` and `month` allow
+specifying 3 letter, uppercase week day and moth names such as `MON`, `TUE`,
+etc and `JAN`, `FEB`, ...
+
+The job is only run when all specified conditions are met. Omitting a field
+is the same as specifying `*`.
+
+## Named Intervals
+
+Alternatively to the above, the keyword `interval` can be used. The following
+intervals can be specified:
+
+ * `yearly` or `annually` means on every January the first at midnight.
+ * `monthly` means on every first of the month at midnight.
+ * `weekly` means every Sunday at midnight.
+ * `daily` means every day at midnight.
+ * `hourly` means every first minute of the hour.
+
+## Command Specification
+
+To specify *what* should be done once the condition is met, the following
+keywords can be used:
+
+ * `exec` - the command to run. Multiple commands can be grouped
+   using curly braces.
+ * `user` - a user name or ID to set before running the commands.
+ * `group` - a group name or ID to set before running the commands.
+ * `tty` - similar to init service files, the controlling tty or output file
+   for the batch commands. Like init service files, the `truncate` keyword
+   can be used.