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Zoidberg-0.41
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/ zoiduser

NAME

zoiduser - Extended user documentation for zoid

DESCRIPTION

Configuration

The location of config and data files can be installation specific. You can check the location where zoid looks for them with the command zoid --config.

By default zoid uses two run control files: /etc/zoidrc and ~/.zoidrc, these are ordinary perl scripts that can interface with zoid. In general data files are found in ~/.zoid/, /usr/local/share/zoid/ or /usr/share/zoid/ these are called 'data_dirs'.

Of the data dirs the sub dir data contains some hashes with general config values, here the most important is the settings file because this is the first file read, it is evaluated before anything else, even before the run scripts. The hash defined by this file is the settings hash which contains all your run time configuration.

The sub dir plugins can contains config files for various plugins or directories with all files belonging to a plugin. The following plugins are included in the standard distribution:

Buffer

Input buffer for interactive mode, not entirely stable but beats typing on STDIN.

Commands

Ships a collection of standard builtin commands that one would expects to have in a shell.

History

Keeps a log of your doings.

Intel

Takes care of tab expansion.

Prompt

Deprecated but for the time being this plugin allows to include information in your prompt. Will be removed without warning.

In theory you should be able to remove or replace any of these plugins, but you better not try this till a more stable version of zoid.

Settings

The following settings supported by (some) Zoidberg modules. They are housed in the hash ->{settings}. Also the builtin set command acts on this hash.

( FIXME link to doc on set command )

Common Settings

allow_null_glob_expansion

It allows to have wildcard patterns that expand into an empty list. The default behavior is to leave the pattern unchanged when it is syntactically incorrect, or the list of matching pathnames is empty.

noglob

Disable path expansion for shell-like syntax.

hide_private_method

Hide all object methods and data structures which have a name starting with an '_' unless they are asked for explicitly.

hide_hidden_files

Hide all filesystem nodes which have a name starting with a '.' unless they are asked for explicitly.

no_hist

Turn off commandline history logging.

ignoreeof

When this setting is in effect a ^D char, also known as EOF or EOT, won't exit the shell.

Devel Settings

_no_redirection

Disable builtin parsing for redirections. Probably needed if you want to do this yourself.

_no_hardcoded_context

Disable hardcoded contexts like PERL, SH and CMD. This might be useful to make for example a restricted shell.

debug

Turn on _all_ debug messages.

naked_zoid

Don't hide the root object behind clothes for things like tab expansion and the single arrow operator, but show it in full glory.

Syntax

Since the syntax of the Zoidberg shell is completely configurable we can only comment on the syntax as defined by the default config files. The general structure will be the same for most user defined configuration but any markup or token could be changed to render the syntax completely unrecognizable.

The Zoidberg syntax consists of three levels of grouping:

Logical grouping

First the syntax is split into blocks with logical/script delimiters

        [block] && [block] || [block] ; [block]
Pipes and redirections

Once the string is cut into logical blocks each of these blocks is split in sub blocks by pipes and.

        [sub_block] | [sub_block] | [sub_block]
Context blocks

At last for each of these sub-blocks a context is decided like:

        SH      - sh like syntax (only very basic statements)
        CMD     - builtin commands
        PERL    - blocks of perl code

Each is executed differently by a suitable subroutine or application, and all are glued together to form a pipeline.

Contexts

The contexts named below are hardcoded, others can be added by plugins. To disable hardcoded contexts see the _no_hardcoded_context setting.

PERL

Perl is the default context if the whole block is between curly brackets, when the first non-whitespace char of the block matches $,@ or % , when the first word seems to be a subroutine because it has parenthis or when the first word is a perl keyword like 'if', 'while', 'for' etc. These keywords can be configured with the array in ->{settings}{perl_keywords}

        # perl because of reserved word
        zoid> for (0..3) { sleep 1; print $_ . "\n" }
        
        # perl because of dollar sign
        zoid> $self->{settings}{naked_zoid}++
        
        # perl because of parentheses
        zoid> ls(qw/-al/)
        
        # perl because of curlies
        zoid> { open TEST, '<test.dat' }

Perl code can have modifiers after the last curly. Currently supported are :

        n: enclose the expression in a "while STDIN" loop
        p: like 'n' but also print $_ at the end of each loop
        g: grep lines from STDIN that make the expression return non-zero
        
        # example
        zoid> ls -al | { s/^(d)\S+/DIR:/ }g

If you use the "naked" form (without the enclosing curlies) a bit of source filtering is applied rendering a lonesome dereference operator -> with into $self->.

        # Thus
        zoid> ->kill('1230')

        # is the same as
        zoid> $self->kill('1230')
SH

This context is intended to make the Zoidberg shell a little friendlier to people used to shells like bash(1). Also this syntax requires less chars to execute a system command. Only the most basic stuff is implemented, you should use perl for things like flow control. Since the default syntax for pipelines and logic lists is also the same as in "sh like" shells a lot of simple constructs will work as expected.

        # this does what it would in /.*sh/
        zoid> ls -al | grep -v CVS | grep ^d > dirs.txt

Be aware redirections ain't fully supported

Currently only the following operators are defined for redirections : '>', '<' and '>>'.

Quoting does not entirely work like in "sh like" shells. Most importantly, you can't start a quoted block in the middle of a word, if you use quotes you need to quote an entire word.

All words, are subject to parameter- and path-expansion unless they are quoted. For double quoted words only parameter expansion is performed, for single quoted words no expansion is performed at all. Parameter expansion interpolates environment variables. (Path expansion is sometimes also called 'glob expansion')

All parameters can be used as arrays, the colon ':' will be used as element separator. To get one element the form $VAR[$i] is recognized by the parameter expansion, where $i is a null-based integer. The form @VAR is a special case that will be expanded to a word list of all the array elements. To avoid conflicts with things like the 'user@host' format used by many applications this special case can only be used as a separate unquoted word.

        zoid> echo $PATH
        /bin:/usr/bin/:/usr/local/bin
        zoid> echo $PATH[2]
        /usr/local/bin
        zoid> echo @PATH
        /bin /usr/bin/ /usr/local/bin
CMD

This context is not really distinguishable from the SH context, but it is used for builtin commands (perl subs that fake to be a system command). There was need for a separate context for this so built-ins won't have to fork (unless used in a pipeline) and thus can alter the parent environment. Commands are housed in the hash ->{commands} and plugins can add to these very easily.

FIXME

FIXME comment on custom defined contexts

FIXME comment on aliases

Examples

Some system binary, context SH

        zoid> mplayer -vo sdl -ao sdl my_favorite_movie.avi

Perl code between brackets, context PERL

        zoid> { print "This is perl code." }

A subroutine call to an object loaded in Zoidberg, context PERL but with a little source filtering applied.

        zoid> ->Help->help
         -or-
        zoid> ->Help->help('objects')

A builtin command faking to be executable, context CMD

        zoid> cd ..

A custom syntax (SQL) enforced on a block:

        zoid> sql{ SELECT * FROM users WHERE clue > 0 }

And as said all of these can be combined:

        zoid> cd /usr/local && { print "This is perl code." } | less || sql{SELECT * FROM users WHERE clue > 0}

This will first execute cd /usr/local, on succes followed by { print "This is perl code." } | less and if one of these failed we get to see the result of sql{SELECT * FROM users WHERE clue > 0}

This makes the precedence of this example as follows.

        ( ( 1 and ( 2 pipe 3 ) ) or 4 )

        1 = cd /usr/local
        2 = { print "This is perl code." }
        3 = less 
        4 = sql{SELECT * FROM users WHERE clue > 0}

SEE ALSO

perl(1), zoiddevel(1), zoidfaq(1), http://zoidberg.sourceforge.net