Shell::Config::Generate

Portably generate config for any shell

SYNOPSIS

With this start up:

use Shell::Guess;
use Shell::Config::Generate;

my $config = Shell::Config::Generate->new;
$config->comment( 'this is my config file' );
$config->set( FOO => 'bar' );
$config->set_path(
  PERL5LIB => '/foo/bar/lib/perl5',
              '/foo/bar/lib/perl5/perl5/site',
);
$config->append_path(
  PATH => '/foo/bar/bin',
          '/bar/foo/bin',
);

This:

$config->generate_file(Shell::Guess->bourne_shell, 'config.sh');

will generate a config.sh file with this:

# this is my config file
FOO='bar';
export FOO;
PERL5LIB='/foo/bar/lib/perl5:/foo/bar/lib/perl5/perl5/site';
export PERL5LIB;
if [ -n "$PATH" ] ; then
  PATH=$PATH:'/foo/bar/bin:/bar/foo/bin';
  export PATH
else
  PATH='/foo/bar/bin:/bar/foo/bin';
  export PATH;
fi;

and this:

$config->generate_file(Shell::Guess->c_shell, 'config.csh');

will generate a config.csh with this:

# this is my config file
setenv FOO 'bar';
setenv PERL5LIB '/foo/bar/lib/perl5:/foo/bar/lib/perl5/perl5/site';
test "$?PATH" = 0 && setenv PATH '/foo/bar/bin:/bar/foo/bin' || setenv PATH "$PATH":'/foo/bar/bin:/bar/foo/bin';

and this:

$config->generate_file(Shell::Guess->cmd_shell, 'config.cmd');

will generate a config.cmd (Windows cmd.exe script) with this:

rem this is my config file
set FOO=bar
set PERL5LIB=/foo/bar/lib/perl5;/foo/bar/lib/perl5/perl5/site
if defined PATH (set PATH=%PATH%;/foo/bar/bin;/bar/foo/bin) else (set PATH=/foo/bar/bin;/bar/foo/bin)

DESCRIPTION

This module provides an interface for specifying shell configurations for different shell environments without having to worry about the arcane differences between shells such as csh, sh, cmd.exe and command.com.

It does not modify the current environment, but it can be used to create shell configurations which do modify the environment.

This module uses Shell::Guess to represent the different types of shells that are supported. In this way you can statically specify just one or more shells:

#!/usr/bin/perl
use Shell::Guess;
use Shell::Config::Generate;
my $config = Shell::Config::Generate->new;
# ... config config ...
$config->generate_file(Shell::Guess->bourne_shell,  'foo.sh' );
$config->generate_file(Shell::Guess->c_shell,       'foo.csh');
$config->generate_file(Shell::Guess->cmd_shell,     'foo.cmd');
$config->generate_file(Shell::Guess->command_shell, 'foo.bat');

This will create foo.sh and foo.csh versions of the configurations, which can be sourced like so:

#!/bin/sh
. ./foo.sh

or

#!/bin/csh
source foo.csh

It also creates .cmd and .bat files with the same configuration which can be used in Windows. The configuration can be imported back into your shell by simply executing these files:

C:\> foo.cmd

or

C:\> foo.bat

Alternatively you can use the shell that called your Perl script using Shell::Guess's running_shell method, and write the output to standard out.

#!/usr/bin/perl
use Shell::Guess;
use Shell::Config::Generate;
my $config = Shell::Config::Generate->new;
# ... config config ...
print $config->generate(Shell::Guess->running_shell);

If you use this pattern, you can eval the output of your script using your shell's back ticks to import the configuration into the shell.

#!/bin/sh
eval `script.pl`

or

#!/bin/csh
eval `script.pl`

CONSTRUCTOR

new

my $config = Shell::Config::Generate->new;

creates an instance of She::Config::Generate.

METHODS

There are two types of instance methods for this class:

• modifiers

  adjust the configuration in an internal portable format

• generators

  generate shell configuration in a specific format given the internal portable format stored inside the instance.

The idea is that you can create multiple modifications to the environment without worrying about specific shells, then when you are done you can create shell specific versions of those modifications using the generators.

This may be useful for system administrators that must support users that use different shells, with a single configuration generation script written in Perl.

set

$config->set( $name => $value );

Set an environment variable.

set_path

$config->set_path( $name => @values );

Sets an environment variable which is stored in standard 'path' format (Like PATH or PERL5LIB). In UNIX land this is a colon separated list stored as a string. In Windows this is a semicolon separated list stored as a string. You can do the same thing using the set method, but if you do so you have to determine the correct separator.

This will replace the existing path value if it already exists.

append_path

$config->append_path( $name => @values );

Appends to an environment variable which is stored in standard 'path' format. This will create a new environment variable if it doesn't already exist, or add to an existing value.

prepend_path

$config->prepend_path( $name => @values );

Prepend to an environment variable which is stored in standard 'path' format. This will create a new environment variable if it doesn't already exist, or add to an existing value.

comment

$config->comment( $comment );

This will generate a comment in the appropriate format.

note that including comments in your configuration may mean it will not work with the eval backticks method for importing configurations into your shell.

shebang

$config->shebang;
$config->shebang($location);

This will generate a shebang at the beginning of the configuration, making it appropriate for use as a script. For non UNIX shells this will be ignored. If specified, $location will be used as the interpreter location. If it is not specified, then the default location for the shell will be used.

note that the shebang in your configuration may mean it will not work with the eval backticks method for importing configurations into your shell.

echo_off

$config->echo_off;

For DOS/Windows configurations (command.com or cmd.exe), issue this as the first line of the config:

@echo off

echo_on

$config->echo_on;

Turn off the echo off (that is do not put anything at the beginning of the config) for DOS/Windows configurations (command.com or cmd.exe).

set_alias

$config->set_alias( $alias => $command )

Sets the given alias to the given command.

Caveat: some older shells do not support aliases, such as the original bourne shell. This module will generate aliases for those shells anyway, since /bin/sh may actually be a more modern shell that DOES support aliases, so do not use this method unless you can be reasonable sure that the shell you are generating supports aliases. On Windows, for PowerShell, a simple function is used instead of an alias so that arguments may be specified.

set_path_sep

$config->set_path_sep( $sep );

Use $sep as the path separator instead of the shell default path separator (generally : for Unix shells and ; for Windows shells).

Not all characters are supported, it is usually best to stick with the shell default or to use : or ;.

generate

my $command_text = $config->generate;
my $command_text = $config->generate( $shell );

Generate shell configuration code for the given shell. $shell is an instance of Shell::Guess. If $shell is not provided, then this method will use Shell::Guess to guess the shell that called your perl script.

You can also pass in the shell name as a string for $shell. This should correspond to the appropriate name_shell from Shell::Guess. So for csh you would pass in "c" and for tcsh you would pass in "tc", etc.

generate_file

$config->generate_file( $shell, $filename );

Generate shell configuration code for the given shell and write it to the given file. $shell is an instance of Shell::Guess. If there is an IO error it will throw an exception.

FUNCTIONS

win32_space_be_gone

my @new_path_list = win32_space_be_gone( @orig_path_list );

On MSWin32 and cygwin:

Given a list of directory paths (or filenames), this will return an equivalent list of paths pointing to the same file system objects without spaces. To do this Win32::GetShortPathName() is used on to find alternative path names without spaces.

NOTE that this breaks when Windows is told not to create short (8+3) filenames; see http://www.perlmonks.org/?node_id=333930 for a discussion of this behaviour.

In addition, on just Cygwin:

The input paths are first converted from POSIX to Windows paths using Cygwin::posix_to_win_path, and then converted back to POSIX paths using Cygwin::win_to_posix_path.

Elsewhere:

Returns the same list passed into it

cmd_escape_path

my @new_path_list = cmd_escape_path( @orig_path_list )

Given a list of directory paths (or filenames), this will return an equivalent list of paths escaped for cmd.exe and command.com.

powershell_escape_path

my @new_path_list = powershell_escape_path( @orig_path_list )

Given a list of directory paths (or filenames), this will return an equivalent list of paths escaped for PowerShell.

CAVEATS

The test suite tests this module's output against the actual shells that should understand them, if they can be found in the path. You can generate configurations for shells which are not available (for example cmd.exe configurations from UNIX or bourne configurations under windows), but the test suite only tests them if they are found during the build of this module.

The implementation for csh depends on the external command test. As far as I can tell test should be available on all modern flavors of UNIX which are using csh. If anyone can figure out how to prepend or append to path type environment variable without an external command in csh, then a patch would be appreciated.

The incantation for prepending and appending elements to a path on csh probably deserve a comment here. It looks like this:

test "$?PATH" = 0 && setenv PATH '/foo/bar/bin:/bar/foo/bin' || setenv PATH "$PATH":'/foo/bar/bin:/bar/foo/bin';

• one line

  The command is all on one line, and doesn't use if, which is probably more clear and ideomatic. This for example, might make more sense:

  if ( $?PATH == 0 ) then
    setenv PATH '/foo/bar/bin:/bar/foo/bin'
  else
    setenv PATH "$PATH":'/foo/bar/bin:/bar/foo/bin'
  endif
  

  However, this only works if the code interpreted using the csh source command or is included in a csh script inline. If you try to invoke this code using csh eval then it will helpfully convert it to one line and if does not work under csh in one line.

There are probably more clever or prettier ways to append/prepend path environment variables as I am not a shell programmer. Patches welcome.

Only UNIX (bourne, bash, csh, ksh, fish and their derivatives) and Windows (command.com, cmd.exe and PowerShell) are supported so far.

Fish shell support should be considered a tech preview. The Fish shell itself is somewhat in flux, and thus some tests are skipped for the Fish shell since behavior is different for different versions. In particular, new lines in environment variables may not work on newer versions.

Patches welcome for your favorite shell / operating system.

AUTHOR

Author: Graham Ollis plicease@cpan.org

Contributors:

Brad Macpherson (BRAD, brad-mac)

mohawk

COPYRIGHT AND LICENSE

This software is copyright (c) 2017 by Graham Ollis.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.