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.

     * getpwent

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

     * dscl

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

     * 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.

     * ps

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

     * 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.

     * 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).

     * 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:

     * $shell->name = bash

     * $shell->is_bash = 1

     * $shell->is_bourne = 1

     * $shell->is_unix = 1

     * $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:

     * $shell->name = bourne

     * $shell->is_bourne = 1

     * $shell->is_unix = 1

     * $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:

     * $shell->name = c

     * $shell->is_c = 1

     * $shell->is_unix = 1

     * $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:

     * $shell->name = cmd

     * $shell->is_cmd = 1

     * $shell->is_win32 = 1

     * $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:

     * $shell->name = command

     * $shell->is_command = 1

     * $shell->is_win32 = 1

     * $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:

     * $shell->name = dcl

     * $shell->is_dcl = 1

     * $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:

     * $shell->name = fish

     * $shell->is_fish = 1

     * $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:

     * $shell->name = korn

     * $shell->is_korn = 1

     * $shell->is_bourne = 1

     * $shell->is_unix = 1

     * $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:

     * $shell->name = power

     * $shell->is_power = 1

     * $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:

     * $shell->name = tc

     * $shell->is_tc = 1

     * $shell->is_c = 1

     * $shell->is_unix = 1

     * $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:

     * $shell->name = z

     * $shell->is_z = 1

     * $shell->is_bourne = 1

     * $shell->is_unix = 1

     * $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.

     * Linux

     * Cygwin

     * FreeBSD

     * Mac OS X

     * Windows (Strawberry Perl)

     * Solaris (x86)

     * MS-DOS (djgpp)

     * 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 <[email protected]>

   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.

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