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Shell::Guess(3)	      User Contributed Perl Documentation      Shell::Guess(3)

NAME
       Shell::Guess - Make an educated guess about the shell in	use

VERSION
       version 0.09

SYNOPSIS
       guessing	shell which called the Perl script:

	use Shell::Guess;
	my $shell = Shell::Guess->running_shell;
	if($shell->is_c) {
	  print	"setenv	FOO bar\n";
	} elsif($shell->is_bourne) {
	  print	"export	FOO=bar\n";
	}

       guessing	the current user's login shell:

	use Shell::Guess;
	my $shell = Shell::Guess->login_shell;
	print $shell->name, "\n";

       guessing	an arbitrary user's login shell:

	use Shell::Guess;
	my $shell = Shell::Guess->login_shell('bob');
	print $shell->name, "\n";

DESCRIPTION
       Shell::Guess makes a reasonably aggressive attempt to determine the
       shell being employed by the user, either	the shell that executed	the
       perl script directly (the "running" shell), or the users' login shell
       (the "login" shell).  It	does this by a variety of means	available to
       it, depending on	the platform that it is	running	on.

       o   getpwent

	   On UNIXy systems with getpwent, that	can be used to determine the
	   login shell.

       o   dscl

	   Under Mac OS	X getpwent will	typically not provide any useful
	   information,	so the dscl command is used instead.

       o   proc	file systems

	   On UNIXy systems with a proc	filesystems (such as Linux),
	   Shell::Guess	will attempt to	use that to determine the running
	   shell.

       o   ps

	   On UNIXy systems without a proc filesystem, Shell::Guess will use
	   the ps command to determine the running shell.

       o   Win32::Getppid and Win32::Process::List

	   On Windows if these modules are installed they will be used to
	   determine the running shell.	 This method can differentiate between
	   PowerShell, "command.com" and "cmd.exe".

       o   ComSpec

	   If the above	method is inconclusive,	the ComSpec environment
	   variable will be consulted to differentiate between "command.com"
	   or "cmd.exe"	(PowerShell cannot be detected in this manner).

       o   reasonable defaults

	   If the running or login shell cannot	be otherwise determined, a
	   reasonable default for your platform	will be	used as	a fallback.
	   Under OpenVMS this is dcl, Windows 95/98 and	MS-DOS this is
	   command.com and Windows NT/2000/XP/Vista/7 this is cmd.exe.	UNIXy
	   platforms fallback to bourne	shell.

       The intended use	of this	module is to enable a Perl developer to	write
       a script	that generates shell configurations for	the calling shell so
       they can	be imported back into the calling shell	using "eval" and
       backticks or "source".  For example, if your script looks like this:

	#!/usr/bin/perl
	use Shell::Guess;
	my $shell = Shell::Guess->running_shell;
	if($shell->is_bourne) {
	  print	"export	FOO=bar\n";
	} else($shell->is_c) {
	  print	"setenv	FOO bar\n";
	} else {
	  die "I don't support ", $shell->name,	" shell";
	}

       You can then import FOO into your bash or c shell like this:

	% eval `perl script.pl`

       or, you can write the output to a configuration file and	source it:

	% perl script.pl > foo.sh
	% source foo.sh

       Shell::Config::Generate provides	a portable interface for generating
       such shell configurations, and is designed to work with this module.

CLASS METHODS
       These class methods return an instance of Shell::Guess, which can then
       be interrogated by the instance methods in the next section below.

   running_shell
	my $shell = Shell::Guess->running_shell;

       Returns an instance of Shell::Guess based on the	shell which directly
       started the current Perl	script.	 If the	running	shell cannot be
       determined, it will return the login shell.

   login_shell
	my $shell = Shell::Guess->login_shell;
	my $shell = Shell::Guess->login_shell( $username )

       Returns an instance of Shell::Guess for the given user.	If no username
       is specified then the current user will be used.	 If no shell can be
       guessed then a reasonable fallback will be chosen based on your
       platform.

   bash_shell
	my $shell = Shell::Guess->bash_shell;

       Returns an instance of Shell::Guess for bash.

       The following instance methods will return:

       o   $shell->name	= bash

       o   $shell->is_bash = 1

       o   $shell->is_bourne = 1

       o   $shell->is_unix = 1

       o   $shell->default_location = /bin/bash

       All other instance methods will return false

   bourne_shell
	my $shell = Shell::Guess->bourne_shell;

       Returns an instance of Shell::Guess for the bourne shell.

       The following instance methods will return:

       o   $shell->name	= bourne

       o   $shell->is_bourne = 1

       o   $shell->is_unix = 1

       o   $shell->default_location = /bin/sh

       All other instance methods will return false

   c_shell
	my $shell = Shell::Guess->c_shell;

       Returns an instance of Shell::Guess for c shell.

       The following instance methods will return:

       o   $shell->name	= c

       o   $shell->is_c	= 1

       o   $shell->is_unix = 1

       o   $shell->default_location = /bin/csh

       All other instance methods will return false

   cmd_shell
	my $shell = Shell::Guess->cmd_shell;

       Returns an instance of Shell::Guess for the Windows NT cmd shell
       (cmd.exe).

       The following instance methods will return:

       o   $shell->name	= cmd

       o   $shell->is_cmd = 1

       o   $shell->is_win32 = 1

       o   $shell->default_location = C:\Windows\system32\cmd.exe

       All other instance methods will return false

   command_shell
	my $shell = Shell::Guess->command_shell;

       Returns an instance of Shell::Guess for the Windows 95 command shell
       (command.com).

       The following instance methods will return:

       o   $shell->name	= command

       o   $shell->is_command =	1

       o   $shell->is_win32 = 1

       o   $shell->default_location = C:\Windows\system32\command.com

       All other instance methods will return false

   dcl_shell
	my $shell = Shell::Guess->dcl_shell;

       Returns an instance of Shell::Guess for the OpenVMS dcl shell.

       The following instance methods will return:

       o   $shell->name	= dcl

       o   $shell->is_dcl = 1

       o   $shell->is_vms = 1

       All other instance methods will return false

   fish_shell
	my $shell = Shell::Guess->fish_shell;

       Returns an instance of Shell::Guess for the fish	shell.

       The following instance methods will return:

       o   $shell->name	= fish

       o   $shell->is_fish = 1

       o   $shell->is_unix = 1

   korn_shell
	my $shell = Shell::Guess->korn_shell;

       Returns an instance of Shell::Guess for the korn	shell.

       The following instance methods will return:

       o   $shell->name	= korn

       o   $shell->is_korn = 1

       o   $shell->is_bourne = 1

       o   $shell->is_unix = 1

       o   $shell->default_location = /bin/ksh

       All other instance methods will return false

   power_shell
	 my $shell = Shell::Guess->power_shell;

       Returns an instance of Shell::Guess for Microsoft PowerShell (either
       for Windows "powershell.exe" or Unix "pwsh").

       The following instance methods will return:

       o   $shell->name	= power

       o   $shell->is_power = 1

       o   $shell->is_win32 = 1

       All other instance methods will return false

   tc_shell
	my $shell = Shell::Guess->tc_shell;

       Returns an instance of Shell::Guess for tcsh.

       The following instance methods will return:

       o   $shell->name	= tc

       o   $shell->is_tc = 1

       o   $shell->is_c	= 1

       o   $shell->is_unix = 1

       o   $shell->default_location = /bin/tcsh

       All other instance methods will return false

   z_shell
	my $shell = Shell::Guess->z_shell

       Returns an instance of Shell::Guess for zsh.

       The following instance methods will return:

       o   $shell->name	= z

       o   $shell->is_z	= 1

       o   $shell->is_bourne = 1

       o   $shell->is_unix = 1

       o   $shell->default_location = /bin/zsh

       All other instance methods will return false

INSTANCE METHODS
       The normal way to call these is by calling them on the result of	either
       running_shell or	login_shell, but they can also be called as class
       methods,	in which case the currently running shell will be used,	so

	Shell::Guess->is_bourne

       is the same as

	Shell::Guess->running_shell->is_bourne

   is_bash
	my $bool = $shell->is_bash;

       Returns true if the shell is bash.

   is_bourne
	my $bool = $shell->is_bourne;

       Returns true if the shell is the	bourne shell, or a shell which
       supports	bourne syntax (e.g. bash or korn).

   is_c
	my $bool = $shell->is_c;

       Returns true if the shell is csh, or a shell which supports csh syntax
       (e.g. tcsh).

   is_cmd
	my $bool = $shell->is_cmd;

       Returns true if the shell is the	Windows	command.com shell.

   is_command
	my $bool = $shell->is_command;

       Returns true if the shell is the	Windows	cmd.com	shell.

   is_dcl
	my $bool = $shell->is_dcl;

       Returns true if the shell is the	OpenVMS	dcl shell.

   is_fish
	my $bool = $shell->is_fish;

       Returns true if the shell is Fish shell.

   is_korn
	my $bool = $shell->is_korn;

       Returns true if the shell is the	korn shell.

   is_power
	my $bool = $shell->is_power;

       Returns true if the shell is Windows PowerShell.

   is_tc
	my $bool = $shell->is_tc;

       Returns true if the shell is tcsh.

   is_unix
	my $bool = $shell->is_unix;

       Returns true if the shell is traditionally a UNIX shell (e.g. bourne,
       bash, korn)

   is_vms
	my $bool = $shell->is_vms;

       Returns true if the shell is traditionally an OpenVMS shell (e.g. dcl)

   is_win32
	my $bool = $shell->is_win32;

       Returns true if the shell is traditionally a Windows shell
       (command.com, cmd.exe, powershell.exe, pwsh)

   is_z
	my $bool = $shell->is_z;

       Returns true if the shell is zsh

   name
	my $name = $shell->name;

       Returns the name	of the shell.

   default_location
	my $location = $shell->default_location;

       The usual location for this shell, for example /bin/sh for bourne shell
       and /bin/csh for	c shell.  May not be defined for all shells.

CAVEATS
       Shell::Guess shouldn't ever die or crash, instead it will attempt to
       make a guess or use a fallback about either the login or	running	shell
       even on unsupported operating systems.  The fallback is the most	common
       shell on	the particular platform	that you are using, so on UNIXy
       platforms the fallback is bourne, and on	OpenVMS	the fallback is	dcl.

       These are the operating systems that have been tested in	development
       and are most likely to guess reliably.

       o   Linux

       o   Cygwin

       o   FreeBSD

       o   Mac OS X

       o   Windows (Strawberry Perl)

       o   Solaris (x86)

       o   MS-DOS (djgpp)

       o   OpenVMS

	   Always detected as dcl (a more nuanced view of OpenVMS is probably
	   possible, patches welcome).

       UNIXy platforms without a proc filesystem will use Unix::Process	if
       installed, which	will execute ps	to determine the running shell.

       It is pretty easy to fool the ->running_shell method by using fork, or
       if your Perl script is not otherwise being directly executed by the
       shell.

       Patches are welcome to make other platforms work	more reliably.

AUTHOR
       Author: Graham Ollis <plicease@cpan.org>

       Contributors:

       Buddy Burden (BAREFOOT)

       Julien Fiegehenn	(SIMBABQUE)

COPYRIGHT AND LICENSE
       This software is	copyright (c) 2012 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.

perl v5.32.1			  2018-12-07		       Shell::Guess(3)

NAME | VERSION | SYNOPSIS | DESCRIPTION | CLASS METHODS | INSTANCE METHODS | CAVEATS | AUTHOR | COPYRIGHT AND LICENSE

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