SU(1) | General Commands Manual | SU(1) |
su
—
su |
[-dfKlm ] [-c
login-class]
[login[:group]
[shell arguments]] |
su |
[-dfKlm ] [-c
login-class] [:group
[shell arguments]] |
su
allows one user to become another user
login without logging out and in as the new user. If a
group is specified and login is a
member of group, then the group is changed to
group rather than to login's
primary group. If login is omitted and
group is provided (form two above), then
login is assumed to be the current username.
When executed by a user, the login user's
password is requested. When using Kerberos, the password for
login (or for
“login.root”, if no login is provided)
is requested, and su
switches to that user and group
ID after obtaining a Kerberos ticket granting ticket. A shell is then
executed, and any additional shell arguments after the
login name are passed to the shell. su
will resort
to the local password file to find the password for
login if there is a Kerberos error. If
su
is executed by root, no password is requested and
a shell with the appropriate user ID is executed; no additional Kerberos
tickets are obtained.
Alternatively, if the user enters the password "s/key", authentication will use the S/Key one-time password system as described in skey(1). S/Key is a Trademark of Bellcore.
By default, the environment is unmodified with the exception of
LOGNAME
, USER
,
HOME
, SHELL
, and
SU_FROM
. HOME
and
SHELL
are set to the target login's default values.
LOGNAME
and USER
are set to
the target login, unless the target login has a user ID of 0, in which case
they are unmodified. SU_FROM
is set to the caller's
login. The invoked shell is the target login's. With the exception of
SU_FROM
this is the traditional behavior of
su
.
The options are as follows:
-c
-d
-l
, but does not change the current
directory.-f
ENV
, thus preventing the shell from executing the
startup file pointed to by this variable.-K
-l
HOME
, SHELL
,
PATH
, TERM
,
LOGNAME
, USER
, and
SU_FROM
. HOME
,
SHELL
, and SU_FROM
are
modified as above. LOGNAME
and
USER
are set to the target login.
PATH
is set to the path specified in the
/etc/login.conf file (or to the default of
“/usr/bin:/bin:/usr/pkg/bin:/usr/local/bin”
). TERM
is imported from your current environment.
The invoked shell is the target login's, and su
will change directory to the target login's home directory. The
utmp(5),
wtmp(5), and
lastlog(5) databases are
not updated.-
-l
.-m
su
will
fail.The -l
and -m
options are mutually exclusive; the last one specified overrides any
previous ones.
Only users in group “wheel” (normally gid 0), as
listed in /etc/group, can su
to “root”, unless group wheel does not exist or has no
members. (If you do not want anybody to be able to
su
to “root”, make
“root” the only member of group “wheel”, which
is the default.)
For sites with very large user populations, group
“wheel” can contain the names of other groups that will be
considered authorized to su
to
“root”.
By default (unless the prompt is reset by a startup file) the super-user prompt is set to “#” to remind one of its awesome power.
su
the name of the required group can be changed
by setting gname in
pam.conf(5):
auth requisite pam_group.so no_warn group=gname root_only fail_safe
For the non pam(8)
version of su
the same can be achieved by
compiling with SU_GROUP
set to the desired group
name.
su
can be configured so that users in a particular
group can supply their own password to become “root”. For
the pam(8) version of
su
this can be done by adding a line to
pam.conf(5) such as:
auth sufficient pam_group.so no_warn group=gname root_only authenticate
where gname is the name of the desired
group. For the non pam(8)
version of su
the same can be achieved by
compiling with SU_ROOTAUTH
set to the desired
group name.
su
. For the non
pam(8) version of
su
, if SU_INDIRECT_GROUP
is defined, the SU_GROUP and
SU_ROOTAUTH groups are treated as indirect groups.
The group members of those two groups are treated as groups
themselves.su
:
HOME
LOGNAME
su
unless the user ID is 0 (root).PATH
TERM
USER
su
unless the user ID is 0 (root).su
returns the exit status of the executed subshell, or
1 if any error occurred while switching privileges.
su username
To become user username and use environment as if full login would be performed, execute:
su -l username
When a -c
option is included
after the login name it is not a
su
option, because any arguments after the
login are passed to the shell. (See
csh(1),
ksh(1) or
sh(1) for details.) To execute
arbitrary command with privileges of user username,
execute:
su username -c "command args"
su
utility appeared in
Version 1 AT&T UNIX
September 1, 2019 | NetBSD 9.4 |