+++ /dev/null
-%%
-%%
-
-\chapter{Variable Expansion}
-\label{VarsChapter}
-\index[general]{Variable Expansion }
-\index[general]{Expansion!Variable }
-
-% TODO: does the following mean that this should not be in book?
-
-Please note that as of version 1.37, the Variable Expansion
-is deprecated and replaced by Python scripting (not yet
-documented).
-
-Variable expansion is somewhat similar to Unix shell variable expansion.
-Currently (version 1.31), it is used only in format labels, but in the future,
-it will most likely be used in more places.
-
-\section{General Functionality}
-\index[general]{Functionality!General }
-\index[general]{General Functionality }
-
-This is basically a string expansion capability that permits referencing
-variables, indexing arrays, conditional replacement of variables, case
-conversion, substring selection, regular expression matching and replacement,
-character class replacement, padding strings, repeated expansion in a user
-controlled loop, support of arithmetic expressions in the loop start, step and
-end conditions, and recursive expansion.
-
-When using variable expansion characters in a Volume Label Format record, the
-format should always be enclosed in double quotes ({\bf "}).
-
-For example, {\bf \$\{HOME\}} will be replaced by your home directory as
-defined in the environment. If you have defined the variable {\bf xxx} to be
-{\bf Test}, then the reference {\bf \$\{xxx:p/7/Y/r\}} will right pad the
-contents of {\bf xxx} to a length of seven characters filling with the
-character {\bf Y} giving {\bf YYYTest}.
-
-\section{Bacula Variables}
-\index[general]{Bacula Variables }
-\index[general]{Variables!Bacula }
-
-Within Bacula, there are three main classes of variables with some minor
-variations within the classes. The classes are:
-
-\begin{description}
-
-\item [Counters]
- \index[general]{Counters }
- Counters are defined by the {\bf Counter} resources in the Director's conf
-file. The counter can either be a temporary counter that lasts for the
-duration of Bacula's execution, or it can be a variable that is stored in
-the catalog, and thus retains its value from one Bacula execution to another.
-Counter variables may be incremented by postfixing a plus sign ({\bf +} after
-the variable name).
-
-\item [Internal Variables]
- \index[general]{Internal Variables }
- Internal variables are read-only, and may be related to the current job (i.e.
-Job name), or maybe special variables such as the date and time. The
-following variables are available:
-
-\begin{itemize}
-\item [Year] -- the full year
-\item [Month] -- the current month 1-12
-\item [Day] -- the day of the month 1-31
-\item [Hour] -- the hour 0-24
-\item [Minute] -- the current minute 0-59
-\item [Second] -- the current second 0-59
-\item [WeekDay] -- the current day of the week 0-6 with 0 being Sunday
-\item [Job] -- the job name
-\item [general] -- the Director's name
-\item [Level] -- the Job Level
-\item [Type] -- the Job type
-\item [JobId] -- the JobId
-\item [JobName] -- the unique job name composed of Job and date
-\item [Storage] -- the Storage daemon's name
-\item [Client] -- the Client's name
-\item [NumVols] -- the current number of Volumes in the Pool
-\item [Pool] -- the Pool name
-\item [Catalog] -- the Catalog name
-\item [MediaType] -- the Media Type
- \end{itemize}
-
-\item [Environment Variables]
- \index[general]{Environment Variables }
- Environment variables are read-only, and must be defined in the environment
-prior to executing Bacula. Environment variables may be either scalar or an
-array, where the elements of the array are referenced by subscripting the
-variable name (e.g. {\bf \$\{Months[3]\}}). Environment variable arrays are
-defined by separating the elements with a vertical bar ({\bf |}), thus {\bf
-set Months="Jan|Feb|Mar|Apr|..."} defines an environment variable named
-{\bf Month} that will be treated as an array, and the reference {\bf
-\$\{Months[3]\}} will yield {\bf Mar}. The elements of the array can have
-differing lengths.
-\end{description}
-
-\section{Full Syntax}
-\index[general]{Syntax!Full }
-\index[general]{Full Syntax }
-
-Since the syntax is quite extensive, below, you will find the pseudo BNF. The
-special characters have the following meaning:
-
-\footnotesize
-\begin{verbatim}
- ::= definition
- ( ) grouping if the parens are not quoted
- | separates alternatives
- '/' literal / (or any other character)
- CAPS a character or character sequence
- * preceding item can be repeated zero or more times
- ? preceding item can appear zero or one time
- + preceding item must appear one or more times
-\end{verbatim}
-\normalsize
-
-And the pseudo BNF describing the syntax is:
-
-\footnotesize
-\begin{verbatim}
- input ::= ( TEXT
- | variable
- | INDEX_OPEN input INDEX_CLOSE (loop_limits)?
- )*
- variable ::= DELIM_INIT (name|expression)
- name ::= (NAME_CHARS)+
- expression ::= DELIM_OPEN
- (name|variable)+
- (INDEX_OPEN num_exp INDEX_CLOSE)?
- (':' command)*
- DELIM_CLOSE
- command ::= '-' (TEXT_EXP|variable)+
- | '+' (TEXT_EXP|variable)+
- | 'o' NUMBER ('-'|',') (NUMBER)?
- | '#'
- | '*' (TEXT_EXP|variable)+
- | 's' '/' (TEXT_PATTERN)+
- '/' (variable|TEXT_SUBST)*
- '/' ('m'|'g'|'i'|'t')*
- | 'y' '/' (variable|TEXT_SUBST)+
- '/' (variable|TEXT_SUBST)*
- '/'
- | 'p' '/' NUMBER
- '/' (variable|TEXT_SUBST)*
- '/' ('r'|'l'|'c')
- | '%' (name|variable)+
- ('(' (TEXT_ARGS)? ')')?
- | 'l'
- | 'u'
- num_exp ::= operand
- | operand ('+'|'-'|'*'|'/'|'%') num_exp
- operand ::= ('+'|'-')? NUMBER
- | INDEX_MARK
- | '(' num_exp ')'
- | variable
- loop_limits ::= DELIM_OPEN
- (num_exp)? ',' (num_exp)? (',' (num_exp)?)?
- DELIM_CLOSE
- NUMBER ::= ('0'|...|'9')+
- TEXT_PATTERN::= (^('/'))+
- TEXT_SUBST ::= (^(DELIM_INIT|'/'))+
- TEXT_ARGS ::= (^(DELIM_INIT|')'))+
- TEXT_EXP ::= (^(DELIM_INIT|DELIM_CLOSE|':'|'+'))+
- TEXT ::= (^(DELIM_INIT|INDEX_OPEN|INDEX_CLOSE))+
- DELIM_INIT ::= '$'
- DELIM_OPEN ::= '{'
- DELIM_CLOSE ::= '}'
- INDEX_OPEN ::= '['
- INDEX_CLOSE ::= ']'
- INDEX_MARK ::= '#'
- NAME_CHARS ::= 'a'|...|'z'|'A'|...|'Z'|'0'|...|'9'
-\end{verbatim}
-\normalsize
-
-\section{Semantics}
-\index[general]{Semantics }
-
-The items listed in {\bf command} above, which always follow a colon ({\bf :})
-have the following meanings:
-
-\footnotesize
-\begin{verbatim}
- - perform substitution if variable is empty
- + perform substitution if variable is not empty
- o cut out substring of the variable value
- # length of the variable value
- * substitute empty string if the variable value is not empty,
- otherwise substitute the trailing parameter
- s regular expression search and replace. The trailing
- options are: m = multiline, i = case insensitive,
- g = global, t = plain text (no regexp)
- y transpose characters from class A to class B
- p pad variable to l = left, r = right or c = center,
- with second value.
- % special function call (none implemented)
- l lower case the variable value
- u upper case the variable value
-\end{verbatim}
-\normalsize
-
-The {\bf loop\_limits} are start, step, and end values.
-
-A counter variable name followed immediately by a plus ({\bf +}) will cause
-the counter to be incremented by one.
-
-\section{Examples}
-\index[general]{Examples }
-
-To create an ISO date:
-
-\footnotesize
-\begin{verbatim}
- DLT-${Year}-${Month:p/2/0/r}-${Day:p/2/0/r}
-\end{verbatim}
-\normalsize
-
-on 20 June 2003 would give {\bf DLT-2003-06-20}
-
-If you set the environment variable {\bf mon} to
-
-\footnotesize
-\begin{verbatim}
- January|February|March|April|May|...
- File-${mon[${Month}]}/${Day}/${Year}
-\end{verbatim}
-\normalsize
-
-on the first of March would give {\bf File-March/1/2003 }
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