freebsd/sbin/rcorder/rcorder.8

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.\" 	Perry E. Metzger.  All rights reserved.
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.\"	by Perry E. Metzger.
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.Dd June 9, 2008
.Dt RCORDER 8
.Os
.Sh NAME
.Nm rcorder
.Nd print a dependency ordering of interdependent files
.Sh SYNOPSIS
.Nm
.Op Fl k Ar keep
.Op Fl s Ar skip
.Ar
.Sh DESCRIPTION
The
.Nm
utility is designed to print out a dependency ordering of a set of
interdependent files.
Typically it is used to find an execution
sequence for a set of shell scripts in which certain files must be
executed before others.
.Pp
Each file passed to
.Nm
must be annotated with special lines (which look like comments to the
shell) which indicate the dependencies the files have upon certain
points in the sequence, known as
.Dq conditions ,
and which indicate, for each file, which
.Dq conditions
may be expected to be filled by that file.
.Pp
Within each file, a block containing a series of
.Dq Li REQUIRE ,
.Dq Li PROVIDE ,
.Dq Li BEFORE
and
.Dq Li KEYWORD
lines must appear.
The format of the lines is rigid.
Each line must begin with a single
.Ql # ,
followed by a single space, followed by
.Dq Li PROVIDE: ,
.Dq Li REQUIRE: ,
.Dq Li BEFORE: ,
or
.Dq Li KEYWORD: .
No deviation is permitted.
Each dependency line is then followed by a series of conditions,
separated by whitespace.
Multiple
.Dq Li PROVIDE ,
.Dq Li REQUIRE ,
.Dq Li BEFORE
and
.Dq Li KEYWORD
lines may appear, but all such lines must appear in a sequence without
any intervening lines, as once a line that does not follow the format
is reached, parsing stops.
.Pp
The options are as follows:
.Bl -tag -width indent
.It Fl k
Add the specified keyword to the
.Dq "keep list" .
If any
.Fl k
option is given, only those files containing the matching keyword are listed.
.It Fl s
Add the specified keyword to the
.Dq "skip list" .
If any
.Fl s
option is given, files containing the matching keyword are not listed.
.El
.Pp
An example block follows:
.Bd -literal -offset indent
# REQUIRE: networking syslog
# REQUIRE: usr
# PROVIDE: dns nscd
.Ed
.Pp
This block states that the file in which it appears depends upon the
.Dq Li networking ,
.Dq Li syslog ,
and
.Dq Li usr
conditions, and provides the
.Dq Li dns
and
.Dq Li nscd
conditions.
.Pp
A file may contain zero
.Dq Li PROVIDE
lines, in which case it provides no conditions, and may contain zero
.Dq Li REQUIRE
lines, in which case it has no dependencies.
There must be at least one file with no dependencies in the set of
arguments passed to
.Nm
in order for it to find a starting place in the dependency ordering.
.Sh DIAGNOSTICS
The
.Nm
utility may print one of the following error messages and exit with a non-zero
status if it encounters an error while processing the file list.
.Bl -diag
.It "Requirement %s has no providers, aborting."
No file has a
.Dq Li PROVIDE
line corresponding to a condition present in a
.Dq Li REQUIRE
line in another file.
.It "Circular dependency on provision %s, aborting."
A set of files has a circular dependency which was detected while
processing the stated condition.
.It "Circular dependency on file %s, aborting."
A set of files has a circular dependency which was detected while
processing the stated file.
.El
.Sh SEE ALSO
.Xr rc 8
.Sh HISTORY
The
.Nm
utility first appeared in
.Nx 1.5 .
.Sh AUTHORS
.An -nosplit
Written by
.An Perry E. Metzger Aq perry@piermont.com
and
.An Matthew R. Green Aq mrg@eterna.com.au .
.Sh BUGS
The
.Dq Li REQUIRE
keyword is misleading:
It doesn't describe which daemons have to be running before a script
will be started.
It describes which scripts must be placed before it in
the dependency ordering.
For example,
if your script has a
.Dq Li REQUIRE
on
.Dq Li named ,
it means the script must be placed after the 
.Dq Li named
script in the dependency ordering,
not necessarily that it requires
.Xr named 8
to be started or enabled.