package Shell; use 5.006_001; use strict; use warnings; use File::Spec::Functions; our($capture_stderr, $raw, $VERSION, $AUTOLOAD); $VERSION = '0.72_01'; $VERSION = eval $VERSION; 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"}; } } # NOTE: this is used to enable constant folding in # expressions like (OS eq 'MSWin32') and # (OS eq 'os2') just like it happened in 0.6 version # which used eval "string" to install subs on the fly. use constant OS => $^O; =begin private =item B<_make_cmd> $sub = _make_cmd($cmd); $sub = $shell->_make_cmd($cmd); Creates a closure which invokes the system command C<$cmd>. =end private =cut sub _make_cmd { shift if ref $_[0] && $_[0]->isa( 'Shell' ); my $cmd = shift; my $null = File::Spec::Functions::devnull(); $Shell::capture_stderr ||= 0; # closing over $^O, $cmd, and $null return sub { 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 (OS 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 = ; close READ; waitpid $pid, 0; @ret; } else { local($/) = undef; my $ret = ; close READ; waitpid $pid, 0; $ret; } } else { my $a; my @arr = @_; unless( $Shell::raw ){ if (OS 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: $!\n"; if (wantarray) { my @ret = ; close SUBPROC; # XXX Oughta use a destructor. @ret; } else { local($/) = undef; my $ret = ; close SUBPROC; $ret; } } }; } sub AUTOLOAD { shift if ref $_[0] && $_[0]->isa( 'Shell' ); my $cmd = $AUTOLOAD; $cmd =~ s/^.*:://; no strict 'refs'; *$AUTOLOAD = _make_cmd($cmd); goto &$AUTOLOAD; } 1; __END__ =head1 NAME Shell - run shell commands transparently within perl =head1 SYNOPSIS use Shell qw(cat ps cp); $passwd = cat('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 operator, or by calling C 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 (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, C and C, C and C, C, C, C, C etc. Using Shell.pm while importing C creates a subroutine C in the namespace of the importing package. Calling C with arguments C, C,... results in a shell command C, 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 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 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 1, the module will attempt to capture the standard error output of the process as well. This is done by adding C<2E&1> to the command line, so don't try this on a system not supporting this redirection. Setting $Shell::capture_stderr to -1 will send standard error to the bit bucket (i.e., the equivalent of adding C<2E/dev/null> to the command line). The same caveat regarding redirection applies. 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 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", "", "world"); print $foo; $passwd = cat(". Changes for OO syntax and bug fixes by Casey West . C<$Shell::raw> and pod rewrite by Wolfgang Laun. Rewritten to use closures rather than C by Adriano Ferreira. =cut