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 32  .\" $Id$
 33  .\"
 34  .Dd January 12, 2006
 35  .Dt SU 1
 36  .Os HEIMDAL
 37  .Sh NAME
 38  .Nm su
 39  .Nd substitute user identity
 40  .Sh SYNOPSIS
 41  .Nm su
 42  .Op Fl K | Fl Fl no-kerberos
 43  .Op Fl f
 44  .Op Fl l | Fl Fl full
 45  .Op Fl m
 46  .Oo Fl i Ar instance \*(Ba Xo
 47  .Fl Fl instance= Ns Ar instance
 48  .Xc
 49  .Oc
 50  .Oo Fl c Ar command \*(Ba Xo
 51  .Fl Fl command= Ns Ar command
 52  .Xc
 53  .Oc
 54  .Op Ar login Op Ar "shell arguments"
 55  .Sh DESCRIPTION
 56  .Nm su
 57  will use Kerberos authentication provided that an instance for the
 58  user wanting to change effective UID is present in a file named
 59  .Pa .k5login
 60  in the target user id's home directory
 61  .Pp
 62  A special case exists where
 63  .Ql root Ap s
 64  .Pa ~/.k5login
 65  needs to contain an entry for:
 66  .Ql user Ns / Ns Ao instance Ac Ns @ Ns REALM
 67  for
 68  .Nm su
 69  to succed (where
 70  .Aq instance
 71  is
 72  .Ql root
 73  unless changed with
 74  .Fl i ) .
 75  .Pp
 76  In the absence of either an entry for current user in said file or
 77  other problems like missing
 78  .Ql host/hostname@REALM
 79  keys in the system's
 80  keytab, or user typing the wrong password,
 81  .Nm su
 82  will fall back to traditional
 83  .Pa /etc/passwd
 84  authentication.
 85  .Pp
 86  When using
 87  .Pa /etc/passwd
 88  authentication,
 89  .Nm su
 90  allows
 91  .Ql root
 92  access only to members of the group
 93  .Ql wheel ,
 94  or to any user (with knowledge of the
 95  .Ql root
 96  password) if that group
 97  does not exist, or has no members.
 98  .Pp
 99  The options are as follows:
100  .Bl -item -width Ds
101  .It
102  .Fl K ,
103  .Fl Fl no-kerberos
104  don't use Kerberos.
105  .It
106  .Fl f
107  don't read .cshrc.
108  .It
109  .Fl l ,
110  .Fl Fl full
111  simulate full login.
112  .It
113  .Fl m
114  leave environment unmodified.
115  .It
116  .Fl i Ar instance ,
117  .Fl Fl instance= Ns Ar instance
118  root instance to use.
119  .It
120  .Fl c Ar command ,
121  .Fl Fl command= Ns Ar command
122  command to execute.
123  .El