While
working on UBUNTU your may incur in a situation where you need to
login as root to execute some task. When you login as sudo you may get
error like: "you are not sudoer list". This ideally due to reason that
when you are trying to log for first time, root as a user is not
enabled. Do make root as user ans to enable logging as root. One has to
activate root account in new UBUNTU machine it is not activated by
default.
Execute command to activate root and set password
sudo passwd root
How to add user in sudoer list, is common problem new linux user faces.
Here is answer of this question.
vikram@vikram-Satellite-C640:~$ sudo ls -l /etc/sudoers
-r--r----- 1 root root 723 Jan 31 2012 /etc/sudoers
vikram@vikram-Satellite-C640:~$ sudo vi /etc/sudoers
vikram@vikram-Satellite-C640:~$ sudo visudo
GNU nano 2.2.6 File: /etc/sudoers.tmp
#
# This file MUST be edited with the 'visudo' command as root.
#
# Please consider adding local content in /etc/sudoers.d/ instead of
# directly modifying this file.
#
# See the man page for details on how to write a sudoers file.
#
Defaults env_reset
Defaults secure_path="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
# Host alias specification
# User alias specification
# Cmnd alias specification
# User privilege specification
root ALL=(ALL:ALL) ALL
# Members of the admin group may gain root privileges
%admin ALL=(ALL) ALL
# Allow members of group sudo to execute any command
%sudo ALL=(ALL:ALL) ALL
# See sudoers(5) for more information on "#include" directives:
#includedir /etc/sudoers.d
[ Read 29 lines ]
^G Get Help ^O WriteOut ^R Read File ^Y Prev Page ^K Cut Text ^C Cur Pos
^X Exit ^J Justify ^W Where Is ^V Next Page ^U UnCut Text ^T To Spell
vikram@vikram-Satellite-C640:~$ sudo visudo
and add below line press CTRL +X to and "Y" to save the file. Please check the file name prior to pressing "Y" file name should ideally be "/etc/sudoers"
If file successfully over written it means command your saved is fine.
user ALL=(ALL)ALL
visudo usually parse the command you are saving against any error otherwise it you will not be able to save.
Now adding a user is sudoer list is done :)
To learn more about visudo you can open man page of visduo. Below is the man page listing
VISUDO(8) MAINTENANCE COMMANDS VISUDO(8)
NAME
visudo - edit the sudoers file
SYNOPSIS
visudo [-chqsV] [-f sudoers]
DESCRIPTION
visudo edits the sudoers file in a safe fashion, analogous to vipw(8). visudo locks the sudoers file against multiple simultaneous
edits, provides basic sanity checks, and checks for parse errors. If the sudoers file is currently being edited you will receive a
message to try again later.
There is a hard-coded list of one or more editors that visudo will use set at compile-time that may be overridden via the editor
sudoers Default variable. This list defaults to "/usr/local/bin/vi". Normally, visudo does not honor the VISUAL or EDITOR
environment variables unless they contain an editor in the aforementioned editors list. However, if visudo is configured with the
--with-env-editor option or the env_editor Default variable is set in sudoers, visudo will use any the editor defines by VISUAL or
EDITOR. Note that this can be a security hole since it allows the user to execute any program they wish simply by setting VISUAL or
EDITOR.
visudo parses the sudoers file after the edit and will not save the changes if there is a syntax error. Upon finding an error,
visudo will print a message stating the line number(s) where the error occurred and the user will receive the "What now?" prompt. At
this point the user may enter "e" to re-edit the sudoers file, "x" to exit without saving the changes, or "Q" to quit and save
changes. The "Q" option should be used with extreme care because if visudo believes there to be a parse error, so will sudo and no
one will be able to sudo again until the error is fixed. If "e" is typed to edit the sudoers file after a parse error has been
detected, the cursor will be placed on the line where the error occurred (if the editor supports this feature).
OPTIONS
visudo accepts the following command line options:
-c Enable check-only mode. The existing sudoers file will be checked for syntax and a message will be printed to the
standard output detailing the status of sudoers. If the syntax check completes successfully, visudo will exit with a
value of 0. If a syntax error is encountered, visudo will exit with a value of 1.
-f sudoers Specify and alternate sudoers file location. With this option visudo will edit (or check) the sudoers file of your
choice, instead of the default, /etc/sudoers. The lock file used is the specified sudoers file with ".tmp" appended to
it. In check-only mode only, the argument to -f may be "-", indicating that sudoers will be read from the standard
input.
-h The -h (help) option causes visudo to print a short help message to the standard output and exit.
-q Enable quiet mode. In this mode details about syntax errors are not printed. This option is only useful when combined
with the -c option.
-s Enable strict checking of the sudoers file. If an alias is used before it is defined, visudo will consider this a parse
error. Note that it is not possible to differentiate between an alias and a host name or user name that consists solely
of uppercase letters, digits, and the underscore ('_') character.
-V The -V (version) option causes visudo to print its version number and exit.
ENVIRONMENT
The following environment variables may be consulted depending on the value of the editor and env_editor sudoers variables:
VISUAL Invoked by visudo as the editor to use
EDITOR Used by visudo if VISUAL is not set
FILES
/etc/sudoers List of who can run what
/etc/sudoers.tmp Lock file for visudo
DIAGNOSTICS
sudoers file busy, try again later.
Someone else is currently editing the sudoers file.
/etc/sudoers.tmp: Permission denied
You didn't run visudo as root.
Can't find you in the passwd database
Your userid does not appear in the system passwd file.
Warning: {User,Runas,Host,Cmnd}_Alias referenced but not defined
Either you are trying to use an undeclare {User,Runas,Host,Cmnd}_Alias or you have a user or host name listed that consists
solely of uppercase letters, digits, and the underscore ('_') character. In the latter case, you can ignore the warnings (sudo
will not complain). In -s (strict) mode these are errors, not warnings.
Warning: unused {User,Runas,Host,Cmnd}_Alias
The specified {User,Runas,Host,Cmnd}_Alias was defined but never used. You may wish to comment out or remove the unused alias.
In -s (strict) mode this is an error, not a warning.
-q Enable quiet mode. In this mode details about syntax errors are not printed. This option is only useful when combined
with the -c option.
-s Enable strict checking of the sudoers file. If an alias is used before it is defined, visudo will consider this a parse
error. Note that it is not possible to differentiate between an alias and a host name or user name that consists solely
of uppercase letters, digits, and the underscore ('_') character.
-V The -V (version) option causes visudo to print its version number and exit.
ENVIRONMENT
The following environment variables may be consulted depending on the value of the editor and env_editor sudoers variables:
VISUAL Invoked by visudo as the editor to use
EDITOR Used by visudo if VISUAL is not set
FILES
/etc/sudoers List of who can run what
/etc/sudoers.tmp Lock file for visudo
DIAGNOSTICS
sudoers file busy, try again later.
Someone else is currently editing the sudoers file.
/etc/sudoers.tmp: Permission denied
You didn't run visudo as root.
Can't find you in the passwd database
Your userid does not appear in the system passwd file.
Warning: {User,Runas,Host,Cmnd}_Alias referenced but not defined
Either you are trying to use an undeclare {User,Runas,Host,Cmnd}_Alias or you have a user or host name listed that consists
solely of uppercase letters, digits, and the underscore ('_') character. In the latter case, you can ignore the warnings (sudo
will not complain). In -s (strict) mode these are errors, not warnings.
Warning: unused {User,Runas,Host,Cmnd}_Alias
The specified {User,Runas,Host,Cmnd}_Alias was defined but never used. You may wish to comment out or remove the unused alias.
In -s (strict) mode this is an error, not a warning.
