MirOS Manual: User::pwent(3p)


User::pwent(3p) Perl Programmers Reference Guide  User::pwent(3p)

NAME

     User::pwent - by-name interface to Perl's built-in getpw*()
     functions

SYNOPSIS

      use User::pwent;
      $pw = getpwnam('daemon')       || die "No daemon user";
      if ( $pw->uid == 1 && $pw->dir =~ m#^/(bin|tmp)?\z#s ) {
          print "gid 1 on root dir";
      }

      $real_shell = $pw->shell || '/bin/sh';

      for (($fullname, $office, $workphone, $homephone) =
             split /\s*,\s*/, $pw->gecos)
      {
         s/&/ucfirst(lc($pw->name))/ge;
      }

      use User::pwent qw(:FIELDS);
      getpwnam('daemon')             || die "No daemon user";
      if ( $pw_uid == 1 && $pw_dir =~ m#^/(bin|tmp)?\z#s ) {
          print "gid 1 on root dir";
      }

      $pw = getpw($whoever);

      use User::pwent qw/:DEFAULT pw_has/;
      if (pw_has(qw[gecos expire quota])) { .... }
      if (pw_has("name uid gid passwd"))  { .... }
      print "Your struct pwd has: ", scalar pw_has(), "\n";

DESCRIPTION

     This module's default exports override the core getpwent(),
     getpwuid(), and getpwnam() functions, replacing them with
     versions that return "User::pwent" objects.  This object has
     methods that return the similarly named structure field name
     from the C's passwd structure from pwd.h, stripped of their
     leading "pw_" parts, namely "name", "passwd", "uid", "gid",
     "change", "age", "quota", "comment", "class", "gecos",
     "dir", "shell", and "expire".  The "passwd", "gecos", and
     "shell" fields are tainted when running in taint mode.

     You may also import all the structure fields directly into
     your namespace as regular variables using the :FIELDS import
     tag.  (Note that this still overrides your core functions.)
     Access these fields as variables named with a preceding
     "pw_" in front their method names.  Thus,
     "$passwd_obj->shell" corresponds to $pw_shell if you import
     the fields.

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User::pwent(3p) Perl Programmers Reference Guide  User::pwent(3p)

     The getpw() function is a simple front-end that forwards a
     numeric argument to getpwuid() and the rest to getpwnam().

     To access this functionality without the core overrides,
     pass the "use" an empty import list, and then access func-
     tion functions with their full qualified names.  The built-
     ins are always still available via the "CORE::"
     pseudo-package.

     System Specifics

     Perl believes that no machine ever has more than one of
     "change", "age", or "quota" implemented, nor more than one
     of either "comment" or "class".  Some machines do not sup-
     port "expire", "gecos", or allegedly, "passwd".  You may
     call these methods no matter what machine you're on, but
     they return "undef" if unimplemented.

     You may ask whether one of these was implemented on the sys-
     tem Perl was built on by asking the importable "pw_has"
     function about them. This function returns true if all
     parameters are supported fields on the build platform, false
     if one or more were not, and raises an exception if you
     asked about a field that Perl never knows how to provide.
     Parameters may be in a space-separated string, or as
     separate arguments.  If you pass no parameters, the function
     returns the list of "struct pwd" fields supported by your
     build platform's C library, as a list in list context, or a
     space-separated string in scalar context.  Note that just
     because your C library had a field doesn't necessarily mean
     that it's fully implemented on that system.

     Interpretation of the "gecos" field varies between systems,
     but traditionally holds 4 comma-separated fields containing
     the user's full name, office location, work phone number,
     and home phone number. An "&" in the gecos field should be
     replaced by the user's properly capitalized login "name".
     The "shell" field, if blank, must be assumed to be /bin/sh.
     Perl does not do this for you.  The "passwd" is one-way
     hashed garble, not clear text, and may not be unhashed save
     by brute-force guessing.  Secure systems use more a more
     secure hashing than DES.  On systems supporting shadow pass-
     word systems, Perl automatically returns the shadow password
     entry when called by a suitably empowered user, even if your
     underlying vendor-provided C library was too short-sighted
     to realize it should do this.

     See passwd(5) and getpwent(3) for details.

NOTE

     While this class is currently implemented using the
     Class::Struct module to build a struct-like class, you

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User::pwent(3p) Perl Programmers Reference Guide  User::pwent(3p)

     shouldn't rely upon this.

AUTHOR

     Tom Christiansen

HISTORY

     March 18th, 2000
         Reworked internals to support better interface to dodgey
         fields than normal Perl function provides.  Added
         pw_has() field.  Improved documentation.

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