AutoGen - The Automated Program Generator: 7.9.4 environment variable presets

[ < ] | [ > ] |  | [ << ] | [ Up ] | [ >> ] |  |  |  |  | [Top] | [Contents] | [Index] | [ ? ]

### 7.9.4 environment variable presets

If the AutoOpts client program specifies `environrc` in its option descriptor file, then environment variables will be used for presetting option state. Variables will be looked for that are named, `PROGRAM_OPTNAME` and `PROGRAM`. `PROGRAM` is the upper cased `C-name` of the program, and `OPTNAME` is the upper cased `C-name` of a specific option. (The `C-name`s are the regular names with all special characters converted to underscores (`_`).)

Option specific environment variables are processed after (and thus take precedence over) the contents of the `PROGRAM` environment variable. The option argument string for these options takes on the string value gotten from the environment. Consequently, you can only have one instance of the `OPTNAME`.

If a particular option may be disabled, then its disabled state is indicated by setting the `PROGRAM_OPTNAME` value to the disablement prefix. So, for example, if the disablement prefix were `dont`, then you can disable the `optname` option by setting the `PROGRAM_OPTNAME`' environment variable to `dont'. See section Common Option Attributes.

The `PROGRAM` environment string is tokenized and parsed much like a command line. Doubly quoted strings have backslash escapes processed the same way they are processed in C program constant strings. Singly quoted strings are "pretty raw" in that backslashes are honored before other backslashes, apostrophes, newlines and cr/newline pairs. The options must be introduced with hyphens in the same way as the command line.

Note that not all options may be preset. Options that are specified with the `no-preset` attribute and the `--help`, `--more-help`, and `--save-opts` auto-supported options may not be preset.

This document was generated by Bruce Korb on August, 12 2006 using texi2html 1.76.