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sudoers



DESCRIPTION

       The sudoers file is composed of two types of entries:
       aliases (basically variables) and user specifications
       (which specify who may run what).  The grammar of sudoers
       will be described below in Extended Backus-Naur Form
       (EBNF).  Don't despair if you don't know what EBNF is; it
       is fairly simple, and the definitions below are annotated.

       Quick guide to EBNF

       EBNF is a concise and exact way of describing the grammar
       of a language.  Each EBNF definition is made up of produc­
       tion rules.  E.g.,

        symbol ::= definition | alternate1 | alternate2 ...

       Each production rule references others and thus makes up a
       grammar for the language.  EBNF also contains the follow­
       ing operators, which many readers will recognize from reg­
       ular expressions.  Do not, however, confuse them with
       "wildcard" characters, which have different meanings.

       ?       Means that the preceding symbol (or group of sym­
               bols) is optional.  That is, it may appear once or
               not at all.

       *       Means that the preceding symbol (or group of sym­
               bols) may appear zero or more times.

       +       Means that the preceding symbol (or group of sym­
               bols) may appear one or more times.

       Parentheses may be used to group symbols together.  For
       clarity, we will use single quotes ('') to designate what
       is a verbatim character string (as opposed to a symbol
       name).

       Aliases

       There are four kinds of aliases: User_Alias, Runas_Alias,
       Host_Alias and Cmnd_Alias.

        Alias ::= 'User_Alias'  User_Alias (':' User_Alias)* |
                  'Runas_Alias' Runas_Alias (':' Runas_Alias)* |
                  'Host_Alias'  Host_Alias (':' Host_Alias)* |
                  'Cmnd_Alias'  Cmnd_Alias (':' Cmnd_Alias)*

        User_Alias ::= NAME '=' User_List

        Runas_Alias ::= NAME '=' Runas_List

        Host_Alias ::= NAME '=' Host_List

       single line, joined by a colon (':').  E.g.,

        Alias_Type NAME = item1, item2, item3 : NAME = item4, item5

       The definitions of what constitutes a valid alias member
       follow.

        User_List ::= User |
                      User ',' User_List

        User ::= '!'* username |
                 '!'* '%'group |
                 '!'* '+'netgroup |
                 '!'* User_Alias

       A User_List is made up of one or more usernames, uids
       (prefixed with '#'), System groups (prefixed with '%'),
       netgroups (prefixed with '+') and other aliases.  Each
       list item may be prefixed with one or more '!' operators.
       An odd number of '!' operators negate the value of the
       item; an even number just cancel each other out.

        Runas_List ::= Runas_User |
                       Runas_User ',' Runas_List

        Runas_User ::= '!'* username |
                       '!'* '#'uid |
                       '!'* '%'group |
                       '!'* +netgroup |
                       '!'* Runas_Alias

       A Runas_List is similar to a User_List except that it can
       also contain uids (prefixed with '#') and instead of
       User_Aliases it can contain Runas_Aliases.

        Host_List ::= Host |
                      Host ',' Host_List

        Host ::= '!'* hostname |
                 '!'* ip_addr |
                 '!'* network(/netmask)? |
                 '!'* '+'netgroup |
                 '!'* Host_Alias

       A Host_List is made up of one or more hostnames, IP
       addresses, network numbers, netgroups (prefixed with '+')
       and other aliases.  Again, the value of an item may be
       negated with the '!' operator.  If you do not specify a
       netmask with a network number, the netmask of the host's
       ethernet interface(s) will be used when matching.  The
       netmask may be specified either in dotted quad notation
       (e.g.  255.255.255.0) or CIDR notation (number of bits,
        Cmnd ::= '!'* commandname |
                 '!'* directory |
                 '!'* Cmnd_Alias

       A Cmnd_List is a list of one or more commandnames, direc­
       tories, and other aliases.  A commandname is a fully qual­
       ified filename which may include shell-style wildcards
       (see `Wildcards' section below).  A simple filename allows
       the user to run the command with any arguments he/she
       wishes.  However, you may also specify command line argu­
       ments (including wildcards).  Alternately, you can specify
       "" to indicate that the command may only be run without
       command line arguments.  A directory is a fully qualified
       pathname ending in a '/'.  When you specify a directory in
       a Cmnd_List, the user will be able to run any file within
       that directory (but not in any subdirectories therein).

       If a Cmnd has associated command line arguments, then the
       arguments in the Cmnd must match exactly those given by
       the user on the command line (or match the wildcards if
       there are any).  Note that the following characters must
       be escaped with a '\' if they are used in command argu­
       ments: ',', ':', '=', '\'.

       Defaults

       Certain configuration options may be changed from their
       default values at runtime via one or more Default_Entry
       lines.  These may affect all users on any host, all users
       on a specific host, a specific user, or commands being run
       as a specific user.  When multiple entries match, they are
       applied in order.  Where there are conflicting values, the
       last value on a matching line takes effect.

        Default_Type ::= 'Defaults' ||
                         'Defaults' '@' Host ||
                         'Defaults' ':' User ||
                         'Defaults' '>' RunasUser

        Default_Entry ::= Default_Type Parameter_List

        Parameter ::= Parameter '=' Value ||
                      Parameter '+=' Value ||
                      Parameter '-=' Value ||
                      '!'* Parameter ||

       Parameters may be flags, integer values, strings, or
       lists.  Flags are implicitly boolean and can be turned off
       via the '!'  operator.  Some integer, string and list
       parameters may also be used in a boolean context to dis­
       able them.  Values may be enclosed in double quotes (")
       when they contain multiple words.  Special characters may
                   When validating with a One Time Password
                   scheme (S/Key or OPIE), a two-line prompt is
                   used to make it easier to cut and paste the
                   challenge to a local window.  It's not as
                   pretty as the default but some people find it
                   more convenient.  This flag is off by default.

       ignore_dot  If set, sudo will ignore '.' or '' (current
                   dir) in the PATH environment variable; the
                   PATH itself is not modified.  This flag is on
                   by default.

       mail_always Send mail to the mailto user every time a
                   users runs sudo.  This flag is off by default.

       mail_badpass
                   Send mail to the mailto user if the user run­
                   ning sudo does not enter the correct password.
                   This flag is off by default.

       mail_no_user
                   If set, mail will be sent to the mailto user
                   if the invoking user is not in the sudoers
                   file.  This flag is on by default.

       mail_no_host
                   If set, mail will be sent to the mailto user
                   if the invoking user exists in the sudoers
                   file, but is not allowed to run commands on
                   the current host.  This flag is off by
                   default.

       mail_no_perms
                   If set, mail will be sent to the mailto user
                   if the invoking user is allowed to use sudo
                   but the command they are trying is not listed
                   in their sudoers file entry.  This flag is off
                   by default.

       tty_tickets If set, users must authenticate on a per-tty
                   basis.  Normally, sudo uses a directory in the
                   ticket dir with the same name as the user run­
                   ning it.  With this flag enabled, sudo will
                   use a file named for the tty the user is
                   logged in on in that directory.  This flag is
                   on by default.

       lecture     If set, a user will receive a short lecture
                   the first time he/she runs sudo.  This flag is
                   on by default.

       authenticate
                   by default.

       log_year    If set, the four-digit year will be logged in
                   the (non-syslog) sudo log file.  This flag is
                   off by default.

       shell_noargs
                   If set and sudo is invoked with no arguments
                   it acts as if the -s flag had been given.
                   That is, it runs a shell as root (the shell is
                   determined by the SHELL environment variable
                   if it is set, falling back on the shell listed
                   in the invoking user's /etc/passwd entry if
                   not).  This flag is off by default.

       set_home    If set and sudo is invoked with the -s flag
                   the HOME environment variable will be set to
                   the home directory of the target user (which
                   is root unless the -u option is used).  This
                   effectively makes the -s flag imply -H.  This
                   flag is off by default.

       always_set_home
                   If set, sudo will set the HOME environment
                   variable to the home directory of the target
                   user (which is root unless the -u option is
                   used).  This effectively means that the -H
                   flag is always implied.  This flag is off by
                   default.

       path_info   Normally, sudo will tell the user when a com­
                   mand could not be found in their PATH environ­
                   ment variable.  Some sites may wish to disable
                   this as it could be used to gather information
                   on the location of executables that the normal
                   user does not have access to.  The disadvan­
                   tage is that if the executable is simply not
                   in the user's PATH, sudo will tell the user
                   that they are not allowed to run it, which can
                   be confusing.  This flag is off by default.

       preserve_groups
                   By default sudo will initialize the group vec­
                   tor to the list of groups the target user is
                   in.  When preserve_groups is set, the user's
                   existing group vector is left unaltered.  The
                   real and effective group IDs, however, are
                   still set to match the target user.  This flag
                   is off by default.

       fqdn        Set this flag if you want to put fully quali­
                   fied hostnames in the sudoers file.  I.e.,
                   set fqdn.  This flag is off by default.

       insults     If set, sudo will insult users when they enter
                   an incorrect password.  This flag is on by
                   default.

       requiretty  If set, sudo will only run when the user is
                   logged in to a real tty.  This will disallow
                   things like "rsh somehost sudo ls" since
                   rsh(1) does not allocate a tty.  Because it is
                   not possible to turn off echo when there is no
                   tty present, some sites may with to set this
                   flag to prevent a user from entering a visible
                   password.  This flag is off by default.

       env_editor  If set, visudo will use the value of the EDI­
                   TOR or VISUAL environment variables before
                   falling back on the default editor list.  Note
                   that this may create a security hole as it
                   allows the user to run any arbitrary command
                   as root without logging.  A safer alternative
                   is to place a colon-separated list of editors
                   in the editor variable.  visudo will then only
                   use the EDITOR or VISUAL if they match a value
                   specified in editor.  This flag is on by
                   default.

       rootpw      If set, sudo will prompt for the root password
                   instead of the password of the invoking user.
                   This flag is off by default.

       runaspw     If set, sudo will prompt for the password of
                   the user defined by the runas_default option
                   (defaults to root) instead of the password of
                   the invoking user.  This flag is off by
                   default.

       targetpw    If set, sudo will prompt for the password of
                   the user specified by the -u flag (defaults to
                   root) instead of the password of the invoking
                   user.  This flag is off by default.

       set_logname Normally, sudo will set the LOGNAME and USER
                   environment variables to the name of the tar­
                   get user (usually root unless the -u flag is
                   given).  However, since some programs (includ­
                   ing the RCS revision control system) use LOG­
                   NAME to determine the real identity of the
                   user, it may be desirable to change this
                   behavior.  This can be done by negating the
                   set_logname option.


       env_reset   If set, sudo will reset the environment to
                   only contain the following variables: HOME,
                   LOGNAME, PATH, SHELL, TERM, and USER (in addi­
                   tion to the SUDO_* variables).  Of these, only
                   TERM is copied unaltered from the old environ­
                   ment.  The other variables are set to default
                   values (possibly modified by the value of the
                   set_logname option).  If sudo was compiled
                   with the SECURE_PATH option, its value will be
                   used for the PATH environment variable.  Other
                   variables may be preserved with the env_keep
                   option.

       use_loginclass
                   If set, sudo will apply the defaults specified
                   for the target user's login class if one
                   exists.  Only available if sudo is configured
                   with the --with-logincap option.  This flag is
                   off by default.

       Integers:

       passwd_tries
                   The number of tries a user gets to enter
                   his/her password before sudo logs the failure
                   and exits.  The default is 3.

       Integers that can be used in a boolean context:

       loglinelen  Number of characters per line for the file
                   log.  This value is used to decide when to
                   wrap lines for nicer log files.  This has no
                   effect on the syslog log file, only the file
                   log.  The default is 80 (use 0 or negate the
                   option to disable word wrap).

       timestamp_timeout
                   Number of minutes that can elapse before sudo
                   will ask for a passwd again.  The default is
                   5.  Set this to 0 to always prompt for a pass­
                   word.  If set to a value less than 0 the
                   user's timestamp will never expire.  This can
                   be used to allow users to create or delete
                   their own timestamps via sudo -v and sudo -k
                   respectively.

       passwd_timeout
                   Number of minutes before the sudo password
                   prompt times out.  The default is 5, set this
                   to 0 for no password timeout.

                   again. unless insults are enabled.

       timestampdir
                   The directory in which sudo stores its times­
                   tamp files.  The default is /var/run/sudo.

       timestampowner
                   The owner of the timestamp directory and the
                   timestamps stored therein.  The default is
                   root.

       passprompt  The default prompt to use when asking for a
                   password; can be overridden via the -p option
                   or the SUDO_PROMPT environment variable.  The
                   following percent (`%') escapes are supported:

                   %u      expanded to the invoking user's login
                           name

                   %U      expanded to the login name of the user
                           the command will be run as (defaults
                           to root)

                   %h      expanded to the local hostname without
                           the domain name

                   %H      expanded to the local hostname includ­
                           ing the domain name (on if the
                           machine's hostname is fully qualified
                           or the fqdn option is set)

                   %%      two consecutive % characters are col­
                           laped into a single % character

                   The default value is Password:.

       runas_default
                   The default user to run commands as if the -u
                   flag is not specified on the command line.
                   This defaults to root.

       syslog_goodpri
                   Syslog priority to use when user authenticates
                   successfully.  Defaults to notice.

       syslog_badpri
                   Syslog priority to use when user authenticates
                   unsuccessfully.  Defaults to alert.

       editor      A colon (':') separated list of editors
                   allowed to be used with visudo.  visudo will
                   choose the editor that matches the user's USER

       mailerpath  Path to mail program used to send warning
                   mail.  Defaults to the path to sendmail found
                   at configure time.

       mailerflags Flags to use when invoking mailer. Defaults to
                   -t.

       mailto      Address to send warning and error mail to.
                   The address should be enclosed in double
                   quotes (") to protect against sudo interpret­
                   ing the @ sign.  Defaults to root.

       exempt_group
                   Users in this group are exempt from password
                   and PATH requirements.  This is not set by
                   default.

       verifypw    This option controls when a password will be
                   required when a user runs sudo with the -v
                   flag.  It has the following possible values:

                   all     All the user's sudoers entries for the
                           current host must have the NOPASSWD
                           flag set to avoid entering a password.

                   any     At least one of the user's sudoers
                           entries for the current host must have
                           the NOPASSWD flag set to avoid enter­
                           ing a password.

                   never   The user need never enter a password
                           to use the -v flag.

                   always  The user must always enter a password
                           to use the -v flag.

                   The default value is `all'.

       listpw      This option controls when a password will be
                   required when a user runs sudo with the -l
                   flag.  It has the following possible values:

                   all     All the user's sudoers entries for the
                           current host must have the NOPASSWD
                           flag set to avoid entering a password.

                   any     At least one of the user's sudoers
                           entries for the current host must have
                           the NOPASSWD flag set to avoid enter­
                           ing a password.

                   bilities in poorly-written programs.  The
                   argument may be a double-quoted, space-sepa­
                   rated list or a single value without dou­
                   ble-quotes.  The list can be replaced, added
                   to, deleted from, or disabled by using the =,
                   +=, -=, and ! operators respectively.  The
                   default list of environment variables to check
                   is printed when sudo is run by root with the
                   -V option.

       env_delete  Environment variables to be removed from the
                   user's environment.  The argument may be a
                   double-quoted, space-separated list or a sin­
                   gle value without double-quotes.  The list can
                   be replaced, added to, deleted from, or dis­
                   abled by using the =, +=, -=, and ! operators
                   respectively.  The default list of environment
                   variables to remove is printed when sudo is
                   run by root with the -V option.  Note that
                   many operating systems will remove potentially
                   dangerous variables from the environment of
                   any setuid process (such as sudo).

       env_keep    Environment variables to be preserved in the
                   user's environment when the env_reset option
                   is in effect.  This allows fine-grained con­
                   trol over the environment sudo-spawned pro­
                   cesses will receive.  The argument may be a
                   double-quoted, space-separated list or a sin­
                   gle value without double-quotes.  The list can
                   be replaced, added to, deleted from, or dis­
                   abled by using the =, +=, -=, and ! operators
                   respectively.  This list has no default mem­
                   bers.

       When logging via syslog(3), sudo accepts the following
       values for the syslog facility (the value of the syslog
       Parameter): authpriv (if your OS supports it), auth, dae­
       mon, user, local0, local1, local2, local3, local4, local5,
       local6, and local7.  The following syslog priorities are
       supported: alert, crit, debug, emerg, err, info, notice,
       and warning.

       User Specification

        User_Spec ::= User_list Host_List '=' Cmnd_Spec_List \
                      (':' User_Spec)*

        Cmnd_Spec_List ::= Cmnd_Spec |
                           Cmnd_Spec ',' Cmnd_Spec_List

        Cmnd_Spec ::= Runas_Spec? ('NOPASSWD:' | 'PASSWD:')? Cmnd

       Runas_Spec in the user specification, a default Runas_Spec
       of root will be used.  A Runas_Spec sets the default for
       commands that follow it.  What this means is that for the
       entry:

        dgb    boulder = (operator) /bin/ls, /bin/kill, /usr/bin/lprm

       The user dgb may run /bin/ls, /bin/kill, and /usr/bin/lprm
       -- but only as operator.  E.g.,

           sudo -u operator /bin/ls.

       It is also possible to override a Runas_Spec later on in
       an entry.  If we modify the entry like so:

        dgb    boulder = (operator) /bin/ls, (root) /bin/kill, /usr/bin/lprm

       Then user dgb is now allowed to run /bin/ls as operator,
       but  /bin/kill and /usr/bin/lprm as root.

       NOPASSWD and PASSWD

       By default, sudo requires that a user authenticate him or
       herself before running a command.  This behavior can be
       modified via the NOPASSWD tag.  Like a Runas_Spec, the
       NOPASSWD tag sets a default for the commands that follow
       it in the Cmnd_Spec_List.  Conversely, the PASSWD tag can
       be used to reverse things.  For example:

        ray    rushmore = NOPASSWD: /bin/kill, /bin/ls, /usr/bin/lprm

       would allow the user ray to run /bin/kill, /bin/ls, and
       /usr/bin/lprm as root on the machine rushmore as root
       without authenticating himself.  If we only want ray to be
       able to run /bin/kill without a password the entry would
       be:

        ray    rushmore = NOPASSWD: /bin/kill, PASSWD: /bin/ls, /usr/bin/lprm

       Note, however, that the PASSWD tag has no effect on users
       who are in the group specified by the exempt_group option.

       By default, if the NOPASSWD tag is applied to any of the
       entries for a user on the current host, he or she will be
       able to run sudo -l without a password.  Additionally, a
       user may only run sudo -v without a password if the
       NOPASSWD tag is present for all a user's entries that per­
       tain to the current host.  This behavior may be overridden
       via the verifypw and listpw options.

       Wildcards (aka meta characters):

               used to escape special characters such as: "*",
               "?", "[", and "}".

       Note that a forward slash ('/') will not be matched by
       wildcards used in the pathname.  When matching the command
       line arguments, however, a slash does get matched by wild­
       cards.  This is to make a path like:

           /usr/bin/*

       match /usr/bin/who but not /usr/bin/X11/xterm.

       Exceptions to wildcard rules:

       The following exceptions apply to the above rules:

       ""      If the empty string "" is the only command line
               argument in the sudoers entry it means that com­
               mand is not allowed to be run with any arguments.

       Other special characters and reserved words:

       The pound sign ('#') is used to indicate a comment (unless
       it occurs in the context of a user name and is followed by
       one or more digits, in which case it is treated as a uid).
       Both the comment character and any text after it, up to
       the end of the line, are ignored.

       The reserved word ALL is a built in alias that always
       causes a match to succeed.  It can be used wherever one
       might otherwise use a Cmnd_Alias, User_Alias, Runas_Alias,
       or Host_Alias.  You should not try to define your own
       alias called ALL as the built in alias will be used in
       preference to your own.  Please note that using ALL can be
       dangerous since in a command context, it allows the user
       to run any command on the system.

       An exclamation point ('!') can be used as a logical not
       operator both in an alias and in front of a Cmnd.  This
       allows one to exclude certain values.  Note, however, that
       using a ! in conjunction with the built in ALL alias to
       allow a user to run "all but a few" commands rarely works
       as intended (see SECURITY NOTES below).

       Long lines can be continued with a backslash ('\') as the
       last character on the line.

       Whitespace between elements in a list as well as special
       syntactic characters in a User Specification ('=', ':',
       '(', ')') is optional.

       The following characters must be escaped with a backslash
        Runas_Alias    DB = oracle, sybase

        # Host alias specification
        Host_Alias     SPARC = bigtime, eclipse, moet, anchor :\
                       SGI = grolsch, dandelion, black :\
                       ALPHA = widget, thalamus, foobar :\
                       HPPA = boa, nag, python
        Host_Alias     CUNETS = 128.138.0.0/255.255.0.0
        Host_Alias     CSNETS = 128.138.243.0, 128.138.204.0/24, 128.138.242.0
        Host_Alias     SERVERS = master, mail, www, ns
        Host_Alias     CDROM = orion, perseus, hercules

        # Cmnd alias specification
        Cmnd_Alias     DUMPS = /usr/bin/mt, /usr/sbin/dump, /usr/sbin/rdump,\
                               /usr/sbin/restore, /usr/sbin/rrestore
        Cmnd_Alias     KILL = /usr/bin/kill
        Cmnd_Alias     PRINTING = /usr/sbin/lpc, /usr/bin/lprm
        Cmnd_Alias     SHUTDOWN = /usr/sbin/shutdown
        Cmnd_Alias     HALT = /usr/sbin/halt, /usr/sbin/fasthalt
        Cmnd_Alias     REBOOT = /usr/sbin/reboot, /usr/sbin/fastboot
        Cmnd_Alias     SHELLS = /usr/bin/sh, /usr/bin/csh, /usr/bin/ksh, \
                                /usr/local/bin/tcsh, /usr/bin/rsh, \
                                /usr/local/bin/zsh
        Cmnd_Alias     SU = /usr/bin/su

       Here we override some of the compiled in default values.
       We want sudo to log via syslog(3) using the auth facility
       in all cases.  We don't want to subject the full time
       staff to the sudo lecture, user millert need not give a
       password, and we don't want to set the LOGNAME or USER
       environment variables when running commands as root.
       Additionally, on the machines in the SERVERS Host_Alias,
       we keep an additional local log file and make sure we log
       the year in each log line since the log entries will be
       kept around for several years.

        # Override built in defaults
        Defaults               syslog=auth
        Defaults>root          !set_logname
        Defaults:FULLTIMERS    !lecture
        Defaults:millert       !authenticate
        Defaults@SERVERS       log_year, logfile=/var/log/sudo.log

       The User specification is the part that actually deter­
       mines who may run what.

        root           ALL = (ALL) ALL
        %wheel         ALL = (ALL) ALL

       We let root and any user in group wheel run any command on
       any host as any user.

       CSNETS alias (the networks 128.138.243.0, 128.138.204.0,
       and 128.138.242.0).  Of those networks, only 128.138.204.0
       has an explicit netmask (in CIDR notation) indicating it
       is a class C network.  For the other networks in CSNETS,
       the local machine's netmask will be used during matching.

        lisa           CUNETS = ALL

       The user lisa may run any command on any host in the
       CUNETS alias (the class B network 128.138.0.0).

        operator       ALL = DUMPS, KILL, PRINTING, SHUTDOWN, HALT, REBOOT,\
                       /usr/oper/bin/

       The operator user may run commands limited to simple main­
       tenance.  Here, those are commands related to backups,
       killing processes, the printing system, shutting down the
       system, and any commands in the directory /usr/oper/bin/.

        joe            ALL = /usr/bin/su operator

       The user joe may only su(1) to operator.

        pete           HPPA = /usr/bin/passwd [A-z]*, !/usr/bin/passwd root

       The user pete is allowed to change anyone's password
       except for root on the HPPA machines.  Note that this
       assumes passwd(1) does not take multiple usernames on the
       command line.

        bob            SPARC = (OP) ALL : SGI = (OP) ALL

       The user bob may run anything on the SPARC and SGI
       machines as any user listed in the OP Runas_Alias (root
       and operator).

        jim            +biglab = ALL

       The user jim may run any command on machines in the biglab
       netgroup.  Sudo knows that "biglab" is a netgroup due to
       the '+' prefix.

        +secretaries   ALL = PRINTING, /usr/bin/adduser, /usr/bin/rmuser

       Users in the secretaries netgroup need to help manage the
       printers as well as add and remove users, so they are
       allowed to run those commands on all machines.

        fred           ALL = (DB) NOPASSWD: ALL

       The user fred can run commands as any user in the DB
       Runas_Alias (oracle or sybase) without giving a password.
       For any machine in the SERVERS Host_Alias, jill may run
       any commands in the directory /usr/bin/ except for those
       commands belonging to the SU and SHELLS Cmnd_Aliases.

        steve          CSNETS = (operator) /usr/local/op_commands/

       The user steve may run any command in the directory
       /usr/local/op_commands/ but only as user operator.

        matt           valkyrie = KILL

       On his personal workstation, valkyrie, matt needs to be
       able to kill hung processes.

        WEBMASTERS     www = (www) ALL, (root) /usr/bin/su www

       On the host www, any user in the WEBMASTERS User_Alias
       (will, wendy, and wim), may run any command as user www
       (which owns the web pages) or simply su(1) to www.

        ALL            CDROM = NOPASSWD: /sbin/umount /CDROM,\
                       /sbin/mount -o nosuid\,nodev /dev/cd0a /CDROM

       Any user may mount or unmount a CD-ROM on the machines in
       the CDROM Host_Alias (orion, perseus, hercules) without
       entering a password.  This is a bit tedious for users to
       type, so it is a prime candidate for encapsulating in a
       shell script.


SECURITY NOTES

       It is generally not effective to "subtract" commands from
       ALL using the '!' operator.  A user can trivially circum­
       vent this by copying the desired command to a different
       name and then executing that.  For example:

           bill        ALL = ALL, !SU, !SHELLS

       Doesn't really prevent bill from running the commands
       listed in SU or SHELLS since he can simply copy those com­
       mands to a different name, or use a shell escape from an
       editor or other program.  Therefore, these kind of
       restrictions should be considered advisory at best (and
       reinforced by policy).


CAVEATS

       The sudoers file should always be edited by the visudo
       command which locks the file and does grammatical check­
       ing. It is imperative that sudoers be free of syntax
       errors since sudo will not run with a syntactically incor­
       rect sudoers file.

       When using netgroups of machines (as opposed to users), if

1.6.7                     March 13, 2003               SUDOERS(5)
  




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