1Shell::Guess(3)       User Contributed Perl Documentation      Shell::Guess(3)
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NAME

6       Shell::Guess - Make an educated guess about the shell in use
7

VERSION

9       version 0.09
10

SYNOPSIS

12       guessing shell which called the Perl script:
13
14        use Shell::Guess;
15        my $shell = Shell::Guess->running_shell;
16        if($shell->is_c) {
17          print "setenv FOO bar\n";
18        } elsif($shell->is_bourne) {
19          print "export FOO=bar\n";
20        }
21
22       guessing the current user's login shell:
23
24        use Shell::Guess;
25        my $shell = Shell::Guess->login_shell;
26        print $shell->name, "\n";
27
28       guessing an arbitrary user's login shell:
29
30        use Shell::Guess;
31        my $shell = Shell::Guess->login_shell('bob');
32        print $shell->name, "\n";
33

DESCRIPTION

35       Shell::Guess makes a reasonably aggressive attempt to determine the
36       shell being employed by the user, either the shell that executed the
37       perl script directly (the "running" shell), or the users' login shell
38       (the "login" shell).  It does this by a variety of means available to
39       it, depending on the platform that it is running on.
40
41       •   getpwent
42
43           On UNIXy systems with getpwent, that can be used to determine the
44           login shell.
45
46       •   dscl
47
48           Under Mac OS X getpwent will typically not provide any useful
49           information, so the dscl command is used instead.
50
51       •   proc file systems
52
53           On UNIXy systems with a proc filesystems (such as Linux),
54           Shell::Guess will attempt to use that to determine the running
55           shell.
56
57       •   ps
58
59           On UNIXy systems without a proc filesystem, Shell::Guess will use
60           the ps command to determine the running shell.
61
62       •   Win32::Getppid and Win32::Process::List
63
64           On Windows if these modules are installed they will be used to
65           determine the running shell.  This method can differentiate between
66           PowerShell, "command.com" and "cmd.exe".
67
68       •   ComSpec
69
70           If the above method is inconclusive, the ComSpec environment
71           variable will be consulted to differentiate between "command.com"
72           or "cmd.exe" (PowerShell cannot be detected in this manner).
73
74       •   reasonable defaults
75
76           If the running or login shell cannot be otherwise determined, a
77           reasonable default for your platform will be used as a fallback.
78           Under OpenVMS this is dcl, Windows 95/98 and MS-DOS this is
79           command.com and Windows NT/2000/XP/Vista/7 this is cmd.exe.  UNIXy
80           platforms fallback to bourne shell.
81
82       The intended use of this module is to enable a Perl developer to write
83       a script that generates shell configurations for the calling shell so
84       they can be imported back into the calling shell using "eval" and
85       backticks or "source".  For example, if your script looks like this:
86
87        #!/usr/bin/perl
88        use Shell::Guess;
89        my $shell = Shell::Guess->running_shell;
90        if($shell->is_bourne) {
91          print "export FOO=bar\n";
92        } else($shell->is_c) {
93          print "setenv FOO bar\n";
94        } else {
95          die "I don't support ", $shell->name, " shell";
96        }
97
98       You can then import FOO into your bash or c shell like this:
99
100        % eval `perl script.pl`
101
102       or, you can write the output to a configuration file and source it:
103
104        % perl script.pl > foo.sh
105        % source foo.sh
106
107       Shell::Config::Generate provides a portable interface for generating
108       such shell configurations, and is designed to work with this module.
109

CLASS METHODS

111       These class methods return an instance of Shell::Guess, which can then
112       be interrogated by the instance methods in the next section below.
113
114   running_shell
115        my $shell = Shell::Guess->running_shell;
116
117       Returns an instance of Shell::Guess based on the shell which directly
118       started the current Perl script.  If the running shell cannot be
119       determined, it will return the login shell.
120
121   login_shell
122        my $shell = Shell::Guess->login_shell;
123        my $shell = Shell::Guess->login_shell( $username )
124
125       Returns an instance of Shell::Guess for the given user.  If no username
126       is specified then the current user will be used.  If no shell can be
127       guessed then a reasonable fallback will be chosen based on your
128       platform.
129
130   bash_shell
131        my $shell = Shell::Guess->bash_shell;
132
133       Returns an instance of Shell::Guess for bash.
134
135       The following instance methods will return:
136
137       •   $shell->name = bash
138
139       •   $shell->is_bash = 1
140
141       •   $shell->is_bourne = 1
142
143       •   $shell->is_unix = 1
144
145       •   $shell->default_location = /bin/bash
146
147       All other instance methods will return false
148
149   bourne_shell
150        my $shell = Shell::Guess->bourne_shell;
151
152       Returns an instance of Shell::Guess for the bourne shell.
153
154       The following instance methods will return:
155
156       •   $shell->name = bourne
157
158       •   $shell->is_bourne = 1
159
160       •   $shell->is_unix = 1
161
162       •   $shell->default_location = /bin/sh
163
164       All other instance methods will return false
165
166   c_shell
167        my $shell = Shell::Guess->c_shell;
168
169       Returns an instance of Shell::Guess for c shell.
170
171       The following instance methods will return:
172
173       •   $shell->name = c
174
175       •   $shell->is_c = 1
176
177       •   $shell->is_unix = 1
178
179       •   $shell->default_location = /bin/csh
180
181       All other instance methods will return false
182
183   cmd_shell
184        my $shell = Shell::Guess->cmd_shell;
185
186       Returns an instance of Shell::Guess for the Windows NT cmd shell
187       (cmd.exe).
188
189       The following instance methods will return:
190
191       •   $shell->name = cmd
192
193       •   $shell->is_cmd = 1
194
195       •   $shell->is_win32 = 1
196
197       •   $shell->default_location = C:\Windows\system32\cmd.exe
198
199       All other instance methods will return false
200
201   command_shell
202        my $shell = Shell::Guess->command_shell;
203
204       Returns an instance of Shell::Guess for the Windows 95 command shell
205       (command.com).
206
207       The following instance methods will return:
208
209       •   $shell->name = command
210
211       •   $shell->is_command = 1
212
213       •   $shell->is_win32 = 1
214
215       •   $shell->default_location = C:\Windows\system32\command.com
216
217       All other instance methods will return false
218
219   dcl_shell
220        my $shell = Shell::Guess->dcl_shell;
221
222       Returns an instance of Shell::Guess for the OpenVMS dcl shell.
223
224       The following instance methods will return:
225
226       •   $shell->name = dcl
227
228       •   $shell->is_dcl = 1
229
230       •   $shell->is_vms = 1
231
232       All other instance methods will return false
233
234   fish_shell
235        my $shell = Shell::Guess->fish_shell;
236
237       Returns an instance of Shell::Guess for the fish shell.
238
239       The following instance methods will return:
240
241       •   $shell->name = fish
242
243       •   $shell->is_fish = 1
244
245       •   $shell->is_unix = 1
246
247   korn_shell
248        my $shell = Shell::Guess->korn_shell;
249
250       Returns an instance of Shell::Guess for the korn shell.
251
252       The following instance methods will return:
253
254       •   $shell->name = korn
255
256       •   $shell->is_korn = 1
257
258       •   $shell->is_bourne = 1
259
260       •   $shell->is_unix = 1
261
262       •   $shell->default_location = /bin/ksh
263
264       All other instance methods will return false
265
266   power_shell
267         my $shell = Shell::Guess->power_shell;
268
269       Returns an instance of Shell::Guess for Microsoft PowerShell (either
270       for Windows "powershell.exe" or Unix "pwsh").
271
272       The following instance methods will return:
273
274       •   $shell->name = power
275
276       •   $shell->is_power = 1
277
278       •   $shell->is_win32 = 1
279
280       All other instance methods will return false
281
282   tc_shell
283        my $shell = Shell::Guess->tc_shell;
284
285       Returns an instance of Shell::Guess for tcsh.
286
287       The following instance methods will return:
288
289       •   $shell->name = tc
290
291       •   $shell->is_tc = 1
292
293       •   $shell->is_c = 1
294
295       •   $shell->is_unix = 1
296
297       •   $shell->default_location = /bin/tcsh
298
299       All other instance methods will return false
300
301   z_shell
302        my $shell = Shell::Guess->z_shell
303
304       Returns an instance of Shell::Guess for zsh.
305
306       The following instance methods will return:
307
308       •   $shell->name = z
309
310       •   $shell->is_z = 1
311
312       •   $shell->is_bourne = 1
313
314       •   $shell->is_unix = 1
315
316       •   $shell->default_location = /bin/zsh
317
318       All other instance methods will return false
319

INSTANCE METHODS

321       The normal way to call these is by calling them on the result of either
322       running_shell or login_shell, but they can also be called as class
323       methods, in which case the currently running shell will be used, so
324
325        Shell::Guess->is_bourne
326
327       is the same as
328
329        Shell::Guess->running_shell->is_bourne
330
331   is_bash
332        my $bool = $shell->is_bash;
333
334       Returns true if the shell is bash.
335
336   is_bourne
337        my $bool = $shell->is_bourne;
338
339       Returns true if the shell is the bourne shell, or a shell which
340       supports bourne syntax (e.g. bash or korn).
341
342   is_c
343        my $bool = $shell->is_c;
344
345       Returns true if the shell is csh, or a shell which supports csh syntax
346       (e.g. tcsh).
347
348   is_cmd
349        my $bool = $shell->is_cmd;
350
351       Returns true if the shell is the Windows command.com shell.
352
353   is_command
354        my $bool = $shell->is_command;
355
356       Returns true if the shell is the Windows cmd.com shell.
357
358   is_dcl
359        my $bool = $shell->is_dcl;
360
361       Returns true if the shell is the OpenVMS dcl shell.
362
363   is_fish
364        my $bool = $shell->is_fish;
365
366       Returns true if the shell is Fish shell.
367
368   is_korn
369        my $bool = $shell->is_korn;
370
371       Returns true if the shell is the korn shell.
372
373   is_power
374        my $bool = $shell->is_power;
375
376       Returns true if the shell is Windows PowerShell.
377
378   is_tc
379        my $bool = $shell->is_tc;
380
381       Returns true if the shell is tcsh.
382
383   is_unix
384        my $bool = $shell->is_unix;
385
386       Returns true if the shell is traditionally a UNIX shell (e.g. bourne,
387       bash, korn)
388
389   is_vms
390        my $bool = $shell->is_vms;
391
392       Returns true if the shell is traditionally an OpenVMS shell (e.g. dcl)
393
394   is_win32
395        my $bool = $shell->is_win32;
396
397       Returns true if the shell is traditionally a Windows shell
398       (command.com, cmd.exe, powershell.exe, pwsh)
399
400   is_z
401        my $bool = $shell->is_z;
402
403       Returns true if the shell is zsh
404
405   name
406        my $name = $shell->name;
407
408       Returns the name of the shell.
409
410   default_location
411        my $location = $shell->default_location;
412
413       The usual location for this shell, for example /bin/sh for bourne shell
414       and /bin/csh for c shell.  May not be defined for all shells.
415

CAVEATS

417       Shell::Guess shouldn't ever die or crash, instead it will attempt to
418       make a guess or use a fallback about either the login or running shell
419       even on unsupported operating systems.  The fallback is the most common
420       shell on the particular platform that you are using, so on UNIXy
421       platforms the fallback is bourne, and on OpenVMS the fallback is dcl.
422
423       These are the operating systems that have been tested in development
424       and are most likely to guess reliably.
425
426       •   Linux
427
428       •   Cygwin
429
430       •   FreeBSD
431
432       •   Mac OS X
433
434       •   Windows (Strawberry Perl)
435
436       •   Solaris (x86)
437
438       •   MS-DOS (djgpp)
439
440       •   OpenVMS
441
442           Always detected as dcl (a more nuanced view of OpenVMS is probably
443           possible, patches welcome).
444
445       UNIXy platforms without a proc filesystem will use Unix::Process if
446       installed, which will execute ps to determine the running shell.
447
448       It is pretty easy to fool the ->running_shell method by using fork, or
449       if your Perl script is not otherwise being directly executed by the
450       shell.
451
452       Patches are welcome to make other platforms work more reliably.
453

AUTHOR

455       Author: Graham Ollis <plicease@cpan.org>
456
457       Contributors:
458
459       Buddy Burden (BAREFOOT)
460
461       Julien Fiegehenn (SIMBABQUE)
462
464       This software is copyright (c) 2012 by Graham Ollis.
465
466       This is free software; you can redistribute it and/or modify it under
467       the same terms as the Perl 5 programming language system itself.
468
469
470
471perl v5.32.1                      2021-01-27                   Shell::Guess(3)
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