1.2.2 Parameter Mode

In parameter mode, the argument to the function given by the virtual code is a data structure containing environment variables and command line parameters including files, application specific options, and possibly standard input. The result obtained by evaluating the function is either a data structure representing a set of files to be written, which may include standard output, or a sequence of shell commands to be executed, or a combination of both. Parameter mode is indicated whenever either of these conditions is met.

• Any of the parameter mode options appears on the command line preceding the first filename parameter.
  See section Parameter Mode Options.
• At least one additional filename parameter or option follows the first filename parameter, and the option ‘--unparameterized’ does not precede it.

Examples:

avram --map-to-each-file prettyprinter.avm *.c *.h --extra-pretty

In this example, parameter mode is indicated both by the parameter mode option ‘--map-to-each-file’ and by the presence of input file names and the ‘--extra-pretty’ option. The latter is specific to the hypothetical prettyprinter.avm virtual code application, as indicated by its position on the command line, and is therefore passed to it by avram.

cat ~/specfile | avram reportgenerator -v - /var/log/syslog

In this example, a hypothetical parameter mode application reportgenerator is able to read ‘~/specfile’ from standard input because of the - used as a parameter.

avram --parameterized grepenv

In this example, a hypothetical application that searches shell variables is invoked in parameter mode even with no input files or application specific options, because of the ‘--parameterized’ option. Parameter mode invocation is required by the application to give it access to the environment.

avram grepenv --search-targets=PATH,MANPATH

This example shows an application specific option with both a keyword and a parameter list. They suffice to indicate parameter mode without an explicit ‘--parameterized’ option.

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