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User::pwent(3perl) Perl Programmers Reference Guide User::pwent(3perl)
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.
perl v5.34.0 2023-11-23 User::pwent(3perl)
Generated by $Id: phpMan.php,v 4.55 2007/09/05 04:42:51 chedong Exp $ Author: Che Dong
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