Examples of org.clapper.util.text.UnixShellVariableSubstituter

• org.clapper.util.text.UnixShellVariableSubstituter

  The UnixShellVariableSubstituter class implements the VariableSubstituter interface and provides an inline variable substitution capability using a simplified Unix Bourne (or GNU bash) shell variable syntax. This syntax recognizes the "$var", "${var}" and "${var?default} sequences as variable references. For example, given the string (variables in bold):

   file:$user.home/profiles/$PLATFORM/${cfg?config}.txt 

  and the variable values:

   user.home=/home/bmc PLATFORM=freebsd 

  a UnixShellVariableSubstituter will produce the result string (substitutions noted in bold):

   file:/home/bmc/profiles/freebsd/config.txt 

  Notes and Caveats

  1. To include a literal "$" character in a string, precede it with a backslash.
  2. If a variable doesn't have a value, its reference is replaced by an empty string, unless it is of the form ${var?default}. For instance, if variable foo does not have a value, the string $foo will substitute "", ${foo} will substitute "", and ${foo?foo value} will substitute "foo value".
  3. As with all VariableSubstituter classes, an instance of the UnixShellVariableSubstituter class enforces its own variable syntax (Unix Bourne shell-style, in this case), but defers actual variable value resolution to a separate VariableDereferencer object. One consequence of that approach is that variable names may be case-sensitive or case-insensitive, depending on how the supplied VariableDereferencer object interprets variable names.

  It's also possible to configure a UnixShellVariableSubstituter to throw a {@link UndefinedVariableException}, rather than substituting a blank, if a variable is undefined and a default value is not specified. See the {@link #setAbortOnUndefinedVariable} method.

  @see WindowsCmdVariableSubstituter @see VariableDereferencer @see VariableSubstituter @see java.lang.String @version $Revision$ @author Copyright © 2004-2007 Brian M. Clapper

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