perl/lib/Shell.pm

package Shell;
use 5.006_001;
use strict;
use warnings;
use File::Spec::Functions;

our($capture_stderr, $raw, $VERSION, $AUTOLOAD);

$VERSION = '0.6';

sub new { bless \my $foo, shift }
sub DESTROY { }

sub import {
    my $self = shift;
    my ($callpack, $callfile, $callline) = caller;
    my @EXPORT;
    if (@_) {
        @EXPORT = @_;
    } else {
        @EXPORT = 'AUTOLOAD';
    }
    foreach my $sym (@EXPORT) {
        no strict 'refs';
        *{"${callpack}::$sym"} = \&{"Shell::$sym"};
    }
}

sub AUTOLOAD {
    shift if ref $_[0] && $_[0]->isa( 'Shell' );
    my $cmd = $AUTOLOAD;
    $cmd =~ s/^.*:://;
    my $null = File::Spec::Functions::devnull();
    $Shell::capture_stderr ||= 0;
    eval <<"*END*";
        sub $AUTOLOAD {
            shift if ref \$_[0] && \$_[0]->isa( 'Shell' );
            if (\@_ < 1) {
                \$Shell::capture_stderr ==  1 ? `$cmd 2>&1` : 
                \$Shell::capture_stderr == -1 ? `$cmd 2>$null` : 
                `$cmd`;
            } elsif ('$^O' eq 'os2') {
                local(\*SAVEOUT, \*READ, \*WRITE);

                open SAVEOUT, '>&STDOUT' or die;
                pipe READ, WRITE or die;
                open STDOUT, '>&WRITE' or die;
                close WRITE;

                my \$pid = system(1, '$cmd', \@_);
                die "Can't execute $cmd: \$!\\n" if \$pid < 0;

                open STDOUT, '>&SAVEOUT' or die;
                close SAVEOUT;

                if (wantarray) {
                    my \@ret = <READ>;
                    close READ;
                    waitpid \$pid, 0;
                    \@ret;
                } else {
                    local(\$/) = undef;
                    my \$ret = <READ>;
                    close READ;
                    waitpid \$pid, 0;
                    \$ret;
                }
            } else {
                my \$a;
                my \@arr = \@_;
                unless( \$Shell::raw ){
                  if ('$^O' eq 'MSWin32') {
                    # XXX this special-casing should not be needed
                    # if we do quoting right on Windows. :-(
                    #
                    # First, escape all quotes.  Cover the case where we
                    # want to pass along a quote preceded by a backslash
                    # (i.e., C<"param \\""" end">).
                    # Ugly, yup?  You know, windoze.
                    # Enclose in quotes only the parameters that need it:
                    #   try this: c:\> dir "/w"
                    #   and this: c:\> dir /w
                    for (\@arr) {
                        s/"/\\\\"/g;
                        s/\\\\\\\\"/\\\\\\\\"""/g;
                        \$_ = qq["\$_"] if /\\s/;
                    }
                  } else {
                    for (\@arr) {
                        s/(['\\\\])/\\\\\$1/g;
                        \$_ = \$_;
                    }
                  }
                }
                push \@arr, '2>&1'        if \$Shell::capture_stderr ==  1;
                push \@arr, '2>$null' if \$Shell::capture_stderr == -1;
                open(SUBPROC, join(' ', '$cmd', \@arr, '|'))
                    or die "Can't exec $cmd: \$!\\n";
                if (wantarray) {
                    my \@ret = <SUBPROC>;
                    close SUBPROC;      # XXX Oughta use a destructor.
                    \@ret;
                } else {
                    local(\$/) = undef;
                    my \$ret = <SUBPROC>;
                    close SUBPROC;
                    \$ret;
                }
            }
        }
*END*

    die "$@\n" if $@;
    goto &$AUTOLOAD;
}

1;

__END__

=head1 NAME

Shell - run shell commands transparently within perl

=head1 SYNOPSIS

   use Shell qw(cat ps cp);
   $passwd = cat('</etc/passwd');
   @pslines = ps('-ww'),
   cp("/etc/passwd", "/tmp/passwd");

   # object oriented 
   my $sh = Shell->new;
   print $sh->ls('-l');

=head1 DESCRIPTION

=head2 Caveats

This package is included as a show case, illustrating a few Perl features.
It shouldn't be used for production programs. Although it does provide a 
simple interface for obtaining the standard output of arbitrary commands,
there may be better ways of achieving what you need.

Running shell commands while obtaining standard output can be done with the
C<qx/STRING/> operator, or by calling C<open> with a filename expression that
ends with C<|>, giving you the option to process one line at a time.
If you don't need to process standard output at all, you might use C<system>
(in preference of doing a print with the collected standard output).

Since Shell.pm and all of the aforementioned techniques use your system's
shell to call some local command, none of them is portable across different 
systems. Note, however, that there are several built in functions and 
library packages providing portable implementations of functions operating
on files, such as: C<glob>, C<link> and C<unlink>, C<mkdir> and C<rmdir>, 
C<rename>, C<File::Compare>, C<File::Copy>, C<File::Find> etc.

Using Shell.pm while importing C<foo> creates a subroutine C<foo> in the
namespace of the importing package. Calling C<foo> with arguments C<arg1>,
C<arg2>,... results in a shell command C<foo arg1 arg2...>, where the 
function name and the arguments are joined with a blank. (See the subsection 
on Escaping magic characters.) Since the result is essentially a command
line to be passed to the shell, your notion of arguments to the Perl
function is not necessarily identical to what the shell treats as a
command line token, to be passed as an individual argument to the program.
Furthermore, note that this implies that C<foo> is callable by file name
only, which frequently depends on the setting of the program's environment.

Creating a Shell object gives you the opportunity to call any command
in the usual OO notation without requiring you to announce it in the
C<use Shell> statement. Don't assume any additional semantics being
associated with a Shell object: in no way is it similar to a shell
process with its environment or current working directory or any
other setting.

=head2 Escaping Magic Characters

It is, in general, impossible to take care of quoting the shell's
magic characters. For some obscure reason, however, Shell.pm quotes
apostrophes (C<'>) and backslashes (C<\>) on UNIX, and spaces and
quotes (C<">) on Windows.

=head2 Configuration

If you set $Shell::capture_stderr to true, the module will attempt to
capture the standard error output of the process as well. This is
done by adding C<2E<gt>&1> to the command line, so don't try this on
a system not supporting this redirection.

If you set $Shell::raw to true no quoting whatsoever is done.

=head1 BUGS

Quoting should be off by default.

It isn't possible to call shell built in commands, but it can be
done by using a workaround, e.g. shell( '-c', 'set' ).

Capturing standard error does not work on some systems (e.g. VMS).

=head1 AUTHOR

  Date: Thu, 22 Sep 94 16:18:16 -0700
  Message-Id: <9409222318.AA17072@scalpel.netlabs.com>
  To: perl5-porters@isu.edu
  From: Larry Wall <lwall@scalpel.netlabs.com>
  Subject: a new module I just wrote

Here's one that'll whack your mind a little out.

    #!/usr/bin/perl

    use Shell;

    $foo = echo("howdy", "<funny>", "world");
    print $foo;

    $passwd = cat("</etc/passwd");
    print $passwd;

    sub ps;
    print ps -ww;

    cp("/etc/passwd", "/etc/passwd.orig");

That's maybe too gonzo.  It actually exports an AUTOLOAD to the current
package (and uncovered a bug in Beta 3, by the way).  Maybe the usual
usage should be

    use Shell qw(echo cat ps cp);

Larry Wall

Changes by Jenda@Krynicky.cz and Dave Cottle <d.cottle@csc.canterbury.ac.nz>.

Changes for OO syntax and bug fixes by Casey West <casey@geeknest.com>.

C<$Shell::raw> and pod rewrite by Wolfgang Laun.

=cut
Revision:	1.1
Committed:	Thu Jun 30 14:27:08 2005 UTC (21 years, 3 months ago) by root
Branch:	MAIN
CVS Tags:	PERL-5-8-7, HEAD
Branch point for:	PERL
Log Message:	* empty log message *
#	User	Rev	Content
1	root	1.1	package Shell;
2			use 5.006_001;
3			use strict;
4			use warnings;
5			use File::Spec::Functions;
6
7			our($capture_stderr, $raw, $VERSION, $AUTOLOAD);
8
9			$VERSION = '0.6';
10
11			sub new { bless \my $foo, shift }
12			sub DESTROY { }
13
14			sub import {
15			my $self = shift;
16			my ($callpack, $callfile, $callline) = caller;
17			my @EXPORT;
18			if (@_) {
19			@EXPORT = @_;
20			} else {
21			@EXPORT = 'AUTOLOAD';
22			}
23			foreach my $sym (@EXPORT) {
24			no strict 'refs';
25			*{"${callpack}::$sym"} = \&{"Shell::$sym"};
26			}
27			}
28
29			sub AUTOLOAD {
30			shift if ref $_[0] && $_[0]->isa( 'Shell' );
31			my $cmd = $AUTOLOAD;
32			$cmd =~ s/^.*:://;
33			my $null = File::Spec::Functions::devnull();
34			$Shell::capture_stderr \|\|= 0;
35			eval <<"END";
36			sub $AUTOLOAD {
37			shift if ref \$_[0] && \$_[0]->isa( 'Shell' );
38			if (\@_ < 1) {
39			\$Shell::capture_stderr == 1 ? `$cmd 2>&1` :
40			\$Shell::capture_stderr == -1 ? `$cmd 2>$null` :
41			`$cmd`;
42			} elsif ('$^O' eq 'os2') {
43			local(\SAVEOUT, \READ, \*WRITE);
44
45			open SAVEOUT, '>&STDOUT' or die;
46			pipe READ, WRITE or die;
47			open STDOUT, '>&WRITE' or die;
48			close WRITE;
49
50			my \$pid = system(1, '$cmd', \@_);
51			die "Can't execute $cmd: \$!\\n" if \$pid < 0;
52
53			open STDOUT, '>&SAVEOUT' or die;
54			close SAVEOUT;
55
56			if (wantarray) {
57			my \@ret = <READ>;
58			close READ;
59			waitpid \$pid, 0;
60			\@ret;
61			} else {
62			local(\$/) = undef;
63			my \$ret = <READ>;
64			close READ;
65			waitpid \$pid, 0;
66			\$ret;
67			}
68			} else {
69			my \$a;
70			my \@arr = \@_;
71			unless( \$Shell::raw ){
72			if ('$^O' eq 'MSWin32') {
73			# XXX this special-casing should not be needed
74			# if we do quoting right on Windows. :-(
75			#
76			# First, escape all quotes. Cover the case where we
77			# want to pass along a quote preceded by a backslash
78			# (i.e., C<"param \\""" end">).
79			# Ugly, yup? You know, windoze.
80			# Enclose in quotes only the parameters that need it:
81			# try this: c:\> dir "/w"
82			# and this: c:\> dir /w
83			for (\@arr) {
84			s/"/\\\\"/g;
85			s/\\\\\\\\"/\\\\\\\\"""/g;
86			\$_ = qq["\$_"] if /\\s/;
87			}
88			} else {
89			for (\@arr) {
90			s/(['\\\\])/\\\\\$1/g;
91			\$_ = \$_;
92			}
93			}
94			}
95			push \@arr, '2>&1' if \$Shell::capture_stderr == 1;
96			push \@arr, '2>$null' if \$Shell::capture_stderr == -1;
97			open(SUBPROC, join(' ', '$cmd', \@arr, '\|'))
98			or die "Can't exec $cmd: \$!\\n";
99			if (wantarray) {
100			my \@ret = <SUBPROC>;
101			close SUBPROC; # XXX Oughta use a destructor.
102			\@ret;
103			} else {
104			local(\$/) = undef;
105			my \$ret = <SUBPROC>;
106			close SUBPROC;
107			\$ret;
108			}
109			}
110			}
111			END
112
113			die "$@\n" if $@;
114			goto &$AUTOLOAD;
115			}
116
117			1;
118
119			__END__
120
121			=head1 NAME
122
123			Shell - run shell commands transparently within perl
124
125			=head1 SYNOPSIS
126
127			use Shell qw(cat ps cp);
128			$passwd = cat('</etc/passwd');
129			@pslines = ps('-ww'),
130			cp("/etc/passwd", "/tmp/passwd");
131
132			# object oriented
133			my $sh = Shell->new;
134			print $sh->ls('-l');
135
136			=head1 DESCRIPTION
137
138			=head2 Caveats
139
140			This package is included as a show case, illustrating a few Perl features.
141			It shouldn't be used for production programs. Although it does provide a
142			simple interface for obtaining the standard output of arbitrary commands,
143			there may be better ways of achieving what you need.
144
145			Running shell commands while obtaining standard output can be done with the
146			C<qx/STRING/> operator, or by calling C<open> with a filename expression that
147			ends with C<\|>, giving you the option to process one line at a time.
148			If you don't need to process standard output at all, you might use C<system>
149			(in preference of doing a print with the collected standard output).
150
151			Since Shell.pm and all of the aforementioned techniques use your system's
152			shell to call some local command, none of them is portable across different
153			systems. Note, however, that there are several built in functions and
154			library packages providing portable implementations of functions operating
155			on files, such as: C<glob>, C<link> and C<unlink>, C<mkdir> and C<rmdir>,
156			C<rename>, C<File::Compare>, C<File::Copy>, C<File::Find> etc.
157
158			Using Shell.pm while importing C<foo> creates a subroutine C<foo> in the
159			namespace of the importing package. Calling C<foo> with arguments C<arg1>,
160			C<arg2>,... results in a shell command C<foo arg1 arg2...>, where the
161			function name and the arguments are joined with a blank. (See the subsection
162			on Escaping magic characters.) Since the result is essentially a command
163			line to be passed to the shell, your notion of arguments to the Perl
164			function is not necessarily identical to what the shell treats as a
165			command line token, to be passed as an individual argument to the program.
166			Furthermore, note that this implies that C<foo> is callable by file name
167			only, which frequently depends on the setting of the program's environment.
168
169			Creating a Shell object gives you the opportunity to call any command
170			in the usual OO notation without requiring you to announce it in the
171			C<use Shell> statement. Don't assume any additional semantics being
172			associated with a Shell object: in no way is it similar to a shell
173			process with its environment or current working directory or any
174			other setting.
175
176			=head2 Escaping Magic Characters
177
178			It is, in general, impossible to take care of quoting the shell's
179			magic characters. For some obscure reason, however, Shell.pm quotes
180			apostrophes (C<'>) and backslashes (C<\>) on UNIX, and spaces and
181			quotes (C<">) on Windows.
182
183			=head2 Configuration
184
185			If you set $Shell::capture_stderr to true, the module will attempt to
186			capture the standard error output of the process as well. This is
187			done by adding C<2E<gt>&1> to the command line, so don't try this on
188			a system not supporting this redirection.
189
190			If you set $Shell::raw to true no quoting whatsoever is done.
191
192			=head1 BUGS
193
194			Quoting should be off by default.
195
196			It isn't possible to call shell built in commands, but it can be
197			done by using a workaround, e.g. shell( '-c', 'set' ).
198
199			Capturing standard error does not work on some systems (e.g. VMS).
200
201			=head1 AUTHOR
202
203			Date: Thu, 22 Sep 94 16:18:16 -0700
204			Message-Id: <9409222318.AA17072@scalpel.netlabs.com>
205			To: perl5-porters@isu.edu
206			From: Larry Wall <lwall@scalpel.netlabs.com>
207			Subject: a new module I just wrote
208
209			Here's one that'll whack your mind a little out.
210
211			#!/usr/bin/perl
212
213			use Shell;
214
215			$foo = echo("howdy", "<funny>", "world");
216			print $foo;
217
218			$passwd = cat("</etc/passwd");
219			print $passwd;
220
221			sub ps;
222			print ps -ww;
223
224			cp("/etc/passwd", "/etc/passwd.orig");
225
226			That's maybe too gonzo. It actually exports an AUTOLOAD to the current
227			package (and uncovered a bug in Beta 3, by the way). Maybe the usual
228			usage should be
229
230			use Shell qw(echo cat ps cp);
231
232			Larry Wall
233
234			Changes by Jenda@Krynicky.cz and Dave Cottle <d.cottle@csc.canterbury.ac.nz>.
235
236			Changes for OO syntax and bug fixes by Casey West <casey@geeknest.com>.
237
238			C<$Shell::raw> and pod rewrite by Wolfgang Laun.
239
240			=cut