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NAME

Shell - run shell commands transparently within perl
 

SYNOPSIS

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

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

DESCRIPTION

Caveats

Running shell commands while obtaining standard output can be done with the "qx/STRING/" operator, or by calling "open" with a filename expression that ends with "|", 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 "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: "glob", "link" and "unlink", "mkdir" and "rmdir", "rename", "File::Compare", "File::Copy", "File::Find" etc.

Using Shell.pm while importing "foo" creates a subroutine "foo" in the namespace of the importing package. Calling "foo" with arguments "arg1", "arg2",... results in a shell command "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 "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 "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.  

Escaping Magic Characters

Configuration

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

BUGS

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).  

AUTHOR

  Date: Thu, 22 Sep 94 16:18:16 -0700
  Message-Id: <[email protected]>
  To: [email protected]
  From: Larry Wall <[email protected]>
  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 [email protected] and Dave Cottle <[email protected]>.

Changes for OO syntax and bug fixes by Casey West <[email protected]>.

$Shell::raw and pod rewrite by Wolfgang Laun.

Index

NAME

SYNOPSIS

DESCRIPTION

Caveats

Escaping Magic Characters

Configuration

BUGS

AUTHOR

Партнёры:

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