##
##  OSSP rc -- Run-command processor samples (manual page)
##  Copyright (c) 2000-2002 Cable & Wireless Deutschland GmbH
##  Copyright (c) 2000-2002 The OSSP Project <http://www.ossp.org/>
##  Copyright (c) 2000-2002 Ralf S. Engelschall <rse@engelschall.com>
##
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##  any purpose with or without fee is hereby granted, provided that
##  the above copyright notice and this permission notice appear in all
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##
##  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
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##  CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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##  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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##


=pod

=head1 NAME

rc-sample -- B<OSSP rc> Example Use Cases

=head1 DESCRIPTION

This documents typical use cases for B<OSSP rc>.

=head1 USE CASE: OpenPKG Runcommand Facility

This describes how B<OSSP rc> is used as the B<OpenPKG>
(http://www.openpkg.org/) runcommand facility. 

First, the involved files:

=over 4

=item F</cw/etc/rc>

This is just the location of the B<OSSP rc> program.

=item F</cw/etc/rc.cf> 

This is the B<OSSP rc> configuration file, hardcoded into
F</cw/etc/rc> at configure/build time with the Autoconf option
C<--with-config=/cw/etc/rc.cf>. It is installed at B<OpenPKG>
bootstrap time and used read-only.

 #   how to locate RC files
 Locate            /cw/etc/rc.d/rc.%{RCFILE:s/^all$/*/}
 Locate            /cw/local/etc/rc.d/rc.%{RCFILE:s/^all$/*/}

 #   requirements on RC files
 RequireUmask      022
 RequireOwner      cw
 RequireGroup      cw

 #   how to parse RC files
 ParseEnvAss       (?<=^\s*)([a-zA-Z_][a-zA-Z_0-9]*)=(?:"([^"]*)"|'([^']*)'|(\S+))
 ParseSectionDef   (?<=^|\n)%([a-zA-Z][a-zA-Z0-9]*)(\s+-[a-zA-Z]\s*\S+)*\s*\n(.+?)(?=\n%%\S+|$)
 ParseSectionRef   (?<=^\s*|;\s*)@([a-zA-Z][a-zA-Z0-9]*)(\s+[^\n]+)?
 ParseSectionParam (?<=^|\s)-([a-zA-Z])\s*(\S+)
 NameConfig        config
 NameCommon        common
 NameDefault       default
 NameError         error

 Execute           root  %s
 Execute           !root sudo %s
 LineControl       yes

=item F</cw/etc/rc.func> (C<%common> extensions)

This is the B<OpenPKG> Bourne shell script providing a set of reusable
functions. It is installed at B<OpenPKG> bootstrap time and used
read-only.

 opVarIsYes () {
     _var="${1}"
     eval "_val=\"\$${_var}\""
     case "${_val}" in
         [Yy][Ee][Ss] | [Tt][Rr][Uu][Ee] | [Oo][Nn] | 1 )
             unset _var _val
             return 0
             ;;
         [Nn][Oo] | [Ff][Aa][Ll][Ss][Ee] | [Oo][Ff][Ff] | 0 )
             unset _var _val
             return 1
             ;;
         *)
             opWarn "variable \$${_var} is not set properly."
             unset _var _val
             return 1
         ;;
     esac
 }
 opServiceEnabled () {
     opVarIsYes ${1}_enable
 }

=item F</cw/etc/rc.conf> 

This is the B<OpenPKG> configuration script where the administrator
overrides the variables from the script's C<%config> sections. It it
generated (as an empty file) on B<OpenPKG> bootstrap time and manually
edited later to influence the behaviours of the package's runcommand
scripts (here F</cw/etc/rc.d/rc.foo>).

 foo_enable=yes
 foo_flags="--sample"

=item F</cw/etc/rc.d/rc.foo> 

This is the example runcommand script of an B<OpenPKG> package C<foo>.
It is installed by package C<foo> and used read-only.

 #! /cw/etc/rc
 %config
     foo_enable=yes
     foo_flags=""
 %common
     foo_pidfile=/cw/var/foo/foo.pid
 %start -u root -p 100
     if opServiceEnabled foo; then
         /cw/sbin/foo -p $foo_pidfile -S $foo_flags
     fi
 %stop -u root -p 100
     if opServiceEnabled foo; then
         /cw/sbin/foo -p $foo_pidfile -K
     fi
 %restart -u root -p 100
     if opServiceEnabled foo; then
         %stop
         sleep 1
         %start 
     fi
 %env
     if opServiceEnabled foo; then
         FOO=/cw/sbin/foo
         export FOO
     fi

=back

With this setup, the following transactions are possible:

 $ /cw/etc/rc --query "foo enabled: %{foo_enable}"
 foo enabled: yes
 $ _

 $ /cw/etc/rc --config
 Configuration Variable   Effective Value              Default Value
 ------------------------ ------------------------- -- -------------------------
 foo_enable               "yes"                     == "yes"                    
 foo_flags                "--sample"                != ""                    
 $ _ 

 $ /cw/etc/rc -v foo start
 start: foo
 $ _ 

 $ /cw/etc/rc --print foo env
 # /cw/etc/rc.d/rc.foo 3
     foo_enable=yes
     foo_flags=""
 # /cw/etc/rc.conf 1
 foo_enable=yes
 foo_flags="--sample"
 # internal 0
     . /cw/etc/rc.func
 # /cw/etc/rc.d/rc.foo 6
     foo_pidfile=/cw/var/foo/foo.pid
 # /cw/etc/rc.d/rc.foo 22
     if opServiceEnabled foo; then
         FOO="The Foo"
         export FOO
     fi
 $ _

 $ eval `/cw/etc/rc --eval foo env`
 $ print $FOO
 The Foo
 $ _

=head1 USE CASE: Dynamic User Environment (DUE)

=over 4

=item F<$HOME/.bashrc>

 cd () {
     eval `$HOME/bin/rc --eval --conf=$HOME/.duecf $PWD leave`
     builtin cd ${1+"$@"} 
     eval `$HOME/bin/rc --eval --conf=$HOME/.duecf $PWD enter`
 }

=item F<$HOME/.duecf>

 #   how to locate RC files
 Locate        %{RCFILE}/.duerc
 Locate        ${HOME}/.duerc:m/^<dir path="%{RCFILE}">(.*)<\/dir>/i
 Locate        ${HOME}/.duerc.%{RCFILE:s/^\///:s/[\/]/-/g}

 #   restrictions on RC files
 RequireUmask  022
 RequireOwner  ${USER}
 RequireGroup  ${USER:F<user2group>}

 #   how to parse RC files
 Functions     $HOME/.duefunc

=item F<$HOME/.duefunc>

 #   append (or optionally prepend) one or more directories (optionally
 #   have to be existing) to a colon-separated path variable. In case a
 #   directory already exists, it is first removed.
 #
 #   Usage:   duePathAdd [-p] [-e] <variable> <dir> [<dir> ...]
 #   Example: duePathAdd -e PATH /bin /sbin /usr/bin /usr/sbin /usr/ccs/bin
 #
 duePathAdd () {
    _prepend=0
    _exists=0
    while [ $# -gt 0 ]; do
        case $1 in
            -p ) _prepend=1; shift ;;
            -e ) _exists=1;  shift ;;
            *  ) break ;;
        esac
    done
    _var="$1"
    shift
    _edit_del=""
    _edit_add=""
    for _dir in "$@"; do
        if [ ".${_exists}" = .1 ] && [ ! -d "${_dir}" ]; then
            continue
        fi
        _edit_del="${_edit_del} -e 's;^${_dir}\$;;' -e 's;^${_dir}:;;'"
        _edit_del="${_edit_del} -e 's;:${_dir}:;:;' -e 's;:${_dir}\$;;'"
        if [ ".${_prepend}" = .0 ]; then
            _edit_add="${_edit_add} -e 's;\$;:${_dir};'"
        else
            _edit_add="-e 's;^;${_dir}:;' ${_edit_add}"
        fi
    done
    if [ ".${_edit_del}${_edit_add}" != . ]; then
        eval "${_var}=\`echo \"\$${_var}\" | sed ${_edit_del} ${_edit_add}\`"
    fi
    unset _prepend _exists _var _edit_del _edit_add _dir
 }

 #
 #   remove one or more directories from a colon-separated path variable
 #
 #   Usage:   duePathDel <variable> <dir> [<dir> ...]
 #   Example: duePathDel PATH /bin /sbin /usr/bin /usr/sbin /usr/ccs/bin
 #
 duePathDel () {
    _var="$1"
    shift
    _edit=""
    for _dir in "$@"; do
        _edit="${_edit} -e 's;^${_dir}\$;;' -e 's;^${_dir}:;;'"
        _edit="${_edit} -e 's;:${_dir}:;:;' -e 's;:${_dir}\$;;'"
    done
    eval "${_var}=\`echo \"\$${_var}\" | sed ${_edit}\`"
    unset _var _edit _dir
 }


=item F</cw/.duerc>

 <event name=enter>
     duePathAdd PATH            $CWD/bin $CWD/sbin
     duePathAdd MANPATH         $CWD/man
     duePathAdd INFOPATH        $CWD/info
     duePathAdd LD_LIBRARY_PATH $CWD/lib
 </event>
 <event name=leave>
     duePathDel PATH            $CWD/bin $CWD/sbin
     duePathDel MANPATH         $CWD/man
     duePathDel INFOPATH        $CWD/info
     duePathDel LD_LIBRARY_PATH $CWD/lib
 </event>

=item F<$HOME/.dueglobal>
  
 <dir path=/cw>
     <event name=enter>
         duePathAdd PATH            /cw/bin /cw/sbin
         duePathAdd MANPATH         /cw/man
         duePathAdd INFOPATH        /cw/info
         duePathAdd LD_LIBRARY_PATH /cw/lib
     </event>
     <event name=leave>
         duePathDel PATH            /cw/bin /cw/sbin
         duePathDel MANPATH         /cw/man
         duePathDel INFOPATH        /cw/info
         duePathDel LD_LIBRARY_PATH /cw/lib
     </event>
 </dir>
 <dir path=/usr/opkg>
     ...
 </dir>

=cut