Manpages - User_pwent.3perl
Table of Contents
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.
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 function 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 support 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 system 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 password 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 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.