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sudo, sudoedit - execute a command as another user
ssuuddoo --hh | --KK | --kk | --LL | --VV
ssuuddoo --vv [--AAkknnSS] [--aa _a_u_t_h___t_y_p_e] [--gg _g_r_o_u_p _n_a_m_e|_#_g_i_d] [--pp _p_r_o_m_p_t]
[--uu _u_s_e_r_n_a_m_e|_#_u_i_d]
ssuuddoo --ll[[ll]] [--AAkknnSS] [--aa _a_u_t_h___t_y_p_e] [--gg _g_r_o_u_p _n_a_m_e|_#_g_i_d] [--pp _p_r_o_m_p_t]
[--UU _u_s_e_r _n_a_m_e] [--uu _u_s_e_r _n_a_m_e|_#_u_i_d] [_c_o_m_m_a_n_d]
ssuuddoo [--AAbbEEHHnnPPSS] [--aa _a_u_t_h___t_y_p_e] [--CC _f_d] [--cc _c_l_a_s_s|_-]
[--gg _g_r_o_u_p _n_a_m_e|_#_g_i_d] [--pp _p_r_o_m_p_t] [--rr _r_o_l_e] [--tt _t_y_p_e]
[--uu _u_s_e_r _n_a_m_e|_#_u_i_d] [VVAARR=_v_a_l_u_e] [--ii | --ss] [_c_o_m_m_a_n_d]
ssuuddooeeddiitt [--AAnnSS] [--aa _a_u_t_h___t_y_p_e] [--CC _f_d] [--cc _c_l_a_s_s|_-]
[--gg _g_r_o_u_p _n_a_m_e|_#_g_i_d] [--pp _p_r_o_m_p_t] [--uu _u_s_e_r _n_a_m_e|_#_u_i_d] file ...
ssuuddoo allows a permitted user to execute a _c_o_m_m_a_n_d as the superuser or
another user, as specified in the _s_u_d_o_e_r_s file. The real and effective
uid and gid are set to match those of the target user as specified in
the passwd file and the group vector is initialized based on the group
file (unless the --PP option was specified). If the invoking user is
root or if the target user is the same as the invoking user, no
password is required. Otherwise, ssuuddoo requires that users authenticate
themselves with a password by default (NOTE: in the default
configuration this is the user's password, not the root password).
Once a user has been authenticated, a time stamp is updated and the
user may then use sudo without a password for a short period of time (5
minutes unless overridden in _s_u_d_o_e_r_s).
When invoked as ssuuddooeeddiitt, the --ee option (described below), is implied.
ssuuddoo determines who is an authorized user by consulting the file
_/_e_t_c_/_s_u_d_o_e_r_s. By running ssuuddoo with the --vv option, a user can update
the time stamp without running a _c_o_m_m_a_n_d. If a password is required,
ssuuddoo will exit if the user's password is not entered within a
configurable time limit. The default password prompt timeout is 5
If a user who is not listed in the _s_u_d_o_e_r_s file tries to run a command
via ssuuddoo, mail is sent to the proper authorities, as defined at
configure time or in the _s_u_d_o_e_r_s file (defaults to root). Note that
the mail will not be sent if an unauthorized user tries to run sudo
with the --ll or --vv option. This allows users to determine for
themselves whether or not they are allowed to use ssuuddoo.
If ssuuddoo is run by root and the SUDO_USER environment variable is set,
ssuuddoo will use this value to determine who the actual user is. This can
be used by a user to log commands through sudo even when a root shell
has been invoked. It also allows the --ee option to remain useful even
when being run via a sudo-run script or program. Note however, that
1.7.4 July 19, 2010 1
the sudoers lookup is still done for root, not the user specified by
ssuuddoo can log both successful and unsuccessful attempts (as well as
errors) to _s_y_s_l_o_g(3), a log file, or both. By default ssuuddoo will log
via _s_y_s_l_o_g(3) but this is changeable at configure time or via the
_s_u_d_o_e_r_s file.
ssuuddoo accepts the following command line options:
-A Normally, if ssuuddoo requires a password, it will read it from
the current terminal. If the --AA (_a_s_k_p_a_s_s) option is
specified, a (possibly graphical) helper program is
executed to read the user's password and output the
password to the standard output. If the SUDO_ASKPASS
environment variable is set, it specifies the path to the
helper program. Otherwise, the value specified by the
_a_s_k_p_a_s_s option in _s_u_d_o_e_r_s(4) is used.
-a _t_y_p_e The --aa (_a_u_t_h_e_n_t_i_c_a_t_i_o_n _t_y_p_e) option causes ssuuddoo to use the
specified authentication type when validating the user, as
allowed by _/_e_t_c_/_l_o_g_i_n_._c_o_n_f. The system administrator may
specify a list of sudo-specific authentication methods by
adding an "auth-sudo" entry in _/_e_t_c_/_l_o_g_i_n_._c_o_n_f. This
option is only available on systems that support BSD
-b The --bb (_b_a_c_k_g_r_o_u_n_d) option tells ssuuddoo to run the given
command in the background. Note that if you use the --bb
option you cannot use shell job control to manipulate the
-C _f_d Normally, ssuuddoo will close all open file descriptors other
than standard input, standard output and standard error.
The --CC (_c_l_o_s_e _f_r_o_m) option allows the user to specify a
starting point above the standard error (file descriptor
three). Values less than three are not permitted. This
option is only available if the administrator has enabled
the _c_l_o_s_e_f_r_o_m___o_v_e_r_r_i_d_e option in _s_u_d_o_e_r_s(4).
-c _c_l_a_s_s The --cc (_c_l_a_s_s) option causes ssuuddoo to run the specified
command with resources limited by the specified login
class. The _c_l_a_s_s argument can be either a class name as
defined in _/_e_t_c_/_l_o_g_i_n_._c_o_n_f, or a single '-' character.
Specifying a _c_l_a_s_s of - indicates that the command should
be run restricted by the default login capabilities for the
user the command is run as. If the _c_l_a_s_s argument
specifies an existing user class, the command must be run
as root, or the ssuuddoo command must be run from a shell that
is already root. This option is only available on systems
with BSD login classes.
-E The --EE (_p_r_e_s_e_r_v_e _e_n_v_i_r_o_n_m_e_n_t) option will override the
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_e_n_v___r_e_s_e_t option in _s_u_d_o_e_r_s(4)). It is only available when
either the matching command has the SETENV tag or the
_s_e_t_e_n_v option is set in _s_u_d_o_e_r_s(4).
-e The --ee (_e_d_i_t) option indicates that, instead of running a
command, the user wishes to edit one or more files. In
lieu of a command, the string "sudoedit" is used when
consulting the _s_u_d_o_e_r_s file. If the user is authorized by
_s_u_d_o_e_r_s the following steps are taken:
1. Temporary copies are made of the files to be edited
with the owner set to the invoking user.
2. The editor specified by the SUDO_EDITOR, VISUAL or
EDITOR environment variables is run to edit the
temporary files. If none of SUDO_EDITOR, VISUAL or
EDITOR are set, the first program listed in the _e_d_i_t_o_r
_s_u_d_o_e_r_s variable is used.
3. If they have been modified, the temporary files are
copied back to their original location and the
temporary versions are removed.
If the specified file does not exist, it will be created.
Note that unlike most commands run by ssuuddoo, the editor is
run with the invoking user's environment unmodified. If,
for some reason, ssuuddoo is unable to update a file with its
edited version, the user will receive a warning and the
edited copy will remain in a temporary file.
-g _g_r_o_u_p Normally, ssuuddoo sets the primary group to the one specified
by the passwd database for the user the command is being
run as (by default, root). The --gg (_g_r_o_u_p) option causes
ssuuddoo to run the specified command with the primary group
set to _g_r_o_u_p. To specify a _g_i_d instead of a _g_r_o_u_p _n_a_m_e,
use _#_g_i_d. When running commands as a _g_i_d, many shells
require that the '#' be escaped with a backslash ('\'). If
no --uu option is specified, the command will be run as the
invoking user (not root). In either case, the primary
group will be set to _g_r_o_u_p.
-H The --HH (_H_O_M_E) option sets the HOME environment variable to
the homedir of the target user (root by default) as
specified in _p_a_s_s_w_d(4). The default handling of the HOME
environment variable depends on _s_u_d_o_e_r_s(4) settings. By
default, ssuuddoo will set HOME if _e_n_v___r_e_s_e_t or _a_l_w_a_y_s___s_e_t___h_o_m_e
are set, or if _s_e_t___h_o_m_e is set and the --ss option is
specified on the command line.
-h The --hh (_h_e_l_p) option causes ssuuddoo to print a usage message
and exit.
-i [command]
The --ii (_s_i_m_u_l_a_t_e _i_n_i_t_i_a_l _l_o_g_i_n) option runs the shell
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specified in the _p_a_s_s_w_d(4) entry of the target user as a
login shell. This means that login-specific resource files
such as .profile or .login will be read by the shell. If a
command is specified, it is passed to the shell for
execution. Otherwise, an interactive shell is executed.
ssuuddoo attempts to change to that user's home directory
before running the shell. It also initializes the
environment, leaving _D_I_S_P_L_A_Y and _T_E_R_M unchanged, setting
_H_O_M_E, _M_A_I_L, _S_H_E_L_L, _U_S_E_R, _L_O_G_N_A_M_E, and _P_A_T_H, as well as the
contents of _/_e_t_c_/_e_n_v_i_r_o_n_m_e_n_t on Linux and AIX systems. All
other environment variables are removed.
-K The --KK (sure _k_i_l_l) option is like --kk except that it removes
the user's time stamp entirely and may not be used in
conjunction with a command or other option. This option
does not require a password.
-k When used by itself, the --kk (_k_i_l_l) option to ssuuddoo
invalidates the user's time stamp by setting the time on it
to the Epoch. The next time ssuuddoo is run a password will be
required. This option does not require a password and was
added to allow a user to revoke ssuuddoo permissions from a
.logout file.
When used in conjunction with a command or an option that
may require a password, the --kk option will cause ssuuddoo to
ignore the user's time stamp file. As a result, ssuuddoo will
prompt for a password (if one is required by _s_u_d_o_e_r_s) and
will not update the user's time stamp file.
-L The --LL (_l_i_s_t defaults) option will list the parameters that
may be set in a _D_e_f_a_u_l_t_s line along with a short
description for each. This option will be removed from a
future version of ssuuddoo.
-l[l] [_c_o_m_m_a_n_d]
If no _c_o_m_m_a_n_d is specified, the --ll (_l_i_s_t) option will list
the allowed (and forbidden) commands for the invoking user
(or the user specified by the --UU option) on the current
host. If a _c_o_m_m_a_n_d is specified and is permitted by
_s_u_d_o_e_r_s, the fully-qualified path to the command is
displayed along with any command line arguments. If
_c_o_m_m_a_n_d is specified but not allowed, ssuuddoo will exit with a
status value of 1. If the --ll option is specified with an ll
argument (i.e. --llll), or if --ll is specified multiple times,
a longer list format is used.
-n The --nn (_n_o_n_-_i_n_t_e_r_a_c_t_i_v_e) option prevents ssuuddoo from
prompting the user for a password. If a password is
required for the command to run, ssuuddoo will display an error
messages and exit.
-P The --PP (_p_r_e_s_e_r_v_e _g_r_o_u_p _v_e_c_t_o_r) option causes ssuuddoo to
preserve the invoking user's group vector unaltered. By
1.7.4 July 19, 2010 4
default, ssuuddoo will initialize the group vector to the list
of groups the target user is in. The real and effective
group IDs, however, are still set to match the target user.
-p _p_r_o_m_p_t The --pp (_p_r_o_m_p_t) option allows you to override the default
password prompt and use a custom one. The following
percent (`%') escapes are supported:
%H expanded to the local host name including the domain
name (on if the machine's host name is fully qualified
or the _f_q_d_n _s_u_d_o_e_r_s option is set)
%h expanded to the local host name without the domain name
%p expanded to the user whose password is being asked for
(respects the _r_o_o_t_p_w, _t_a_r_g_e_t_p_w and _r_u_n_a_s_p_w flags in
%U expanded to the login name of the user the command will
be run as (defaults to root)
%u expanded to the invoking user's login name
%% two consecutive % characters are collapsed into a
single % character
The prompt specified by the --pp option will override the
system password prompt on systems that support PAM unless
the _p_a_s_s_p_r_o_m_p_t___o_v_e_r_r_i_d_e flag is disabled in _s_u_d_o_e_r_s.
-r _r_o_l_e The --rr (_r_o_l_e) option causes the new (SELinux) security
context to have the role specified by _r_o_l_e.
-S The --SS (_s_t_d_i_n) option causes ssuuddoo to read the password from
the standard input instead of the terminal device. The
password must be followed by a newline character.
-s [command]
The --ss (_s_h_e_l_l) option runs the shell specified by the _S_H_E_L_L
environment variable if it is set or the shell as specified
in _p_a_s_s_w_d(4). If a command is specified, it is passed to
the shell for execution. Otherwise, an interactive shell
is executed.
-t _t_y_p_e The --tt (_t_y_p_e) option causes the new (SELinux) security
context to have the type specified by _t_y_p_e. If no type is
specified, the default type is derived from the specified
-U _u_s_e_r The --UU (_o_t_h_e_r _u_s_e_r) option is used in conjunction with the
--ll option to specify the user whose privileges should be
listed. Only root or a user with ssuuddoo ALL on the current
host may use this option.
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-u _u_s_e_r The --uu (_u_s_e_r) option causes ssuuddoo to run the specified
command as a user other than _r_o_o_t. To specify a _u_i_d
instead of a _u_s_e_r _n_a_m_e, use _#_u_i_d. When running commands as
a _u_i_d, many shells require that the '#' be escaped with a
backslash ('\'). Note that if the _t_a_r_g_e_t_p_w Defaults option
is set (see _s_u_d_o_e_r_s(4)) it is not possible to run commands
with a uid not listed in the password database.
-V The --VV (_v_e_r_s_i_o_n) option causes ssuuddoo to print the version
number and exit. If the invoking user is already root the
--VV option will print out a list of the defaults ssuuddoo was
compiled with as well as the machine's local network
-v If given the --vv (_v_a_l_i_d_a_t_e) option, ssuuddoo will update the
user's time stamp, prompting for the user's password if
necessary. This extends the ssuuddoo timeout for another 5
minutes (or whatever the timeout is set to in _s_u_d_o_e_r_s) but
does not run a command.
-- The ---- option indicates that ssuuddoo should stop processing
command line arguments.
Environment variables to be set for the command may also be passed on
the command line in the form of VVAARR=_v_a_l_u_e, e.g.
LLDD__LLIIBBRRAARRYY__PPAATTHH=_/_u_s_r_/_l_o_c_a_l_/_p_k_g_/_l_i_b. Variables passed on the command
line are subject to the same restrictions as normal environment
variables with one important exception. If the _s_e_t_e_n_v option is set in
_s_u_d_o_e_r_s, the command to be run has the SETENV tag set or the command
matched is ALL, the user may set variables that would overwise be
forbidden. See _s_u_d_o_e_r_s(4) for more information.
Upon successful execution of a program, the exit status from ssuuddoo will
simply be the exit status of the program that was executed.
Otherwise, ssuuddoo quits with an exit value of 1 if there is a
configuration/permission problem or if ssuuddoo cannot execute the given
command. In the latter case the error string is printed to stderr. If
ssuuddoo cannot _s_t_a_t(2) one or more entries in the user's PATH an error is
printed on stderr. (If the directory does not exist or if it is not
really a directory, the entry is ignored and no error is printed.)
This should not happen under normal circumstances. The most common
reason for _s_t_a_t(2) to return "permission denied" is if you are running
an automounter and one of the directories in your PATH is on a machine
that is currently unreachable.
ssuuddoo tries to be safe when executing external commands.
There are two distinct ways to deal with environment variables. By
default, the _e_n_v___r_e_s_e_t _s_u_d_o_e_r_s option is enabled. This causes commands
to be executed with a minimal environment containing TERM, PATH, HOME,
SHELL, LOGNAME, USER and USERNAME in addition to variables from the
1.7.4 July 19, 2010 6
invoking process permitted by the _e_n_v___c_h_e_c_k and _e_n_v___k_e_e_p _s_u_d_o_e_r_s
options. There is effectively a whitelist for environment variables.
If, however, the _e_n_v___r_e_s_e_t option is disabled in _s_u_d_o_e_r_s, any variables
not explicitly denied by the _e_n_v___c_h_e_c_k and _e_n_v___d_e_l_e_t_e options are
inherited from the invoking process. In this case, _e_n_v___c_h_e_c_k and
_e_n_v___d_e_l_e_t_e behave like a blacklist. Since it is not possible to
blacklist all potentially dangerous environment variables, use of the
default _e_n_v___r_e_s_e_t behavior is encouraged.
In all cases, environment variables with a value beginning with () are
removed as they could be interpreted as bbaasshh functions. The list of
environment variables that ssuuddoo allows or denies is contained in the
output of sudo -V when run as root.
Note that the dynamic linker on most operating systems will remove
variables that can control dynamic linking from the environment of
setuid executables, including ssuuddoo. Depending on the operating system
this may include _RLD*, DYLD_*, LD_*, LDR_*, LIBPATH, SHLIB_PATH, and
others. These type of variables are removed from the environment
before ssuuddoo even begins execution and, as such, it is not possible for
ssuuddoo to preserve them.
To prevent command spoofing, ssuuddoo checks "." and "" (both denoting
current directory) last when searching for a command in the user's PATH
(if one or both are in the PATH). Note, however, that the actual PATH
environment variable is _n_o_t modified and is passed unchanged to the
program that ssuuddoo executes.
ssuuddoo will check the ownership of its time stamp directory
(_/_v_a_r_/_a_d_m_/_s_u_d_o by default) and ignore the directory's contents if it is
not owned by root or if it is writable by a user other than root. On
systems that allow non-root users to give away files via _c_h_o_w_n(2), if
the time stamp directory is located in a directory writable by anyone
(e.g., _/_t_m_p), it is possible for a user to create the time stamp
directory before ssuuddoo is run. However, because ssuuddoo checks the
ownership and mode of the directory and its contents, the only damage
that can be done is to "hide" files by putting them in the time stamp
dir. This is unlikely to happen since once the time stamp dir is owned
by root and inaccessible by any other user, the user placing files
there would be unable to get them back out. To get around this issue
you can use a directory that is not world-writable for the time stamps
(_/_v_a_r_/_a_d_m_/_s_u_d_o for instance) or create _/_v_a_r_/_a_d_m_/_s_u_d_o with the
appropriate owner (root) and permissions (0700) in the system startup
ssuuddoo will not honor time stamps set far in the future. Timestamps with
a date greater than current_time + 2 * TIMEOUT will be ignored and sudo
will log and complain. This is done to keep a user from creating
his/her own time stamp with a bogus date on systems that allow users to
give away files.
On systems where the boot time is available, ssuuddoo will also not honor
time stamps from before the machine booted.
1.7.4 July 19, 2010 7
Since time stamp files live in the file system, they can outlive a
user's login session. As a result, a user may be able to login, run a
command with ssuuddoo after authenticating, logout, login again, and run
ssuuddoo without authenticating so long as the time stamp file's
modification time is within 5 minutes (or whatever the timeout is set
to in _s_u_d_o_e_r_s). When the _t_t_y___t_i_c_k_e_t_s option is enabled in _s_u_d_o_e_r_s, the
time stamp has per-tty granularity but still may outlive the user's
session. On Linux systems where the devpts filesystem is used, Solaris
systems with the devices filesystem, as well as other systems that
utilize a devfs filesystem that monotonically increase the inode number
of devices as they are created (such as Mac OS X), ssuuddoo is able to
determine when a tty-based time stamp file is stale and will ignore it.
Administrators should not rely on this feature as it is not universally
Please note that ssuuddoo will normally only log the command it explicitly
runs. If a user runs a command such as sudo su or sudo sh, subsequent
commands run from that shell will _n_o_t be logged, nor will ssuuddoo's access
control affect them. The same is true for commands that offer shell
escapes (including most editors). Because of this, care must be taken
when giving users access to commands via ssuuddoo to verify that the
command does not inadvertently give the user an effective root shell.
For more information, please see the PREVENTING SHELL ESCAPES section
in _s_u_d_o_e_r_s(4).
ssuuddoo utilizes the following environment variables:
EDITOR Default editor to use in --ee (sudoedit) mode if neither
MAIL In --ii mode or when _e_n_v___r_e_s_e_t is enabled in _s_u_d_o_e_r_s, set
to the mail spool of the target user
HOME Set to the home directory of the target user if --ii or
--HH are specified, _e_n_v___r_e_s_e_t or _a_l_w_a_y_s___s_e_t___h_o_m_e are set
in _s_u_d_o_e_r_s, or when the --ss option is specified and
_s_e_t___h_o_m_e is set in _s_u_d_o_e_r_s
PATH Set to a sane value if the _s_e_c_u_r_e___p_a_t_h sudoers option
is set.
SHELL Used to determine shell to run with -s option
SUDO_ASKPASS Specifies the path to a helper program used to read the
password if no terminal is available or if the -A
option is specified.
SUDO_COMMAND Set to the command run by sudo
SUDO_EDITOR Default editor to use in --ee (sudoedit) mode
SUDO_GID Set to the group ID of the user who invoked sudo
1.7.4 July 19, 2010 8
SUDO_PROMPT Used as the default password prompt
SUDO_PS1 If set, PS1 will be set to its value for the program
being run
SUDO_UID Set to the user ID of the user who invoked sudo
SUDO_USER Set to the login of the user who invoked sudo
USER Set to the target user (root unless the --uu option is
VISUAL Default editor to use in --ee (sudoedit) mode if
SUDO_EDITOR is not set
_/_e_t_c_/_s_u_d_o_e_r_s List of who can run what
_/_v_a_r_/_a_d_m_/_s_u_d_o Directory containing time stamps
_/_e_t_c_/_e_n_v_i_r_o_n_m_e_n_t Initial environment for --ii mode on Linux and
Note: the following examples assume suitable _s_u_d_o_e_r_s(4) entries.
To get a file listing of an unreadable directory:
$ sudo ls /usr/local/protected
To list the home directory of user yaz on a machine where the file
system holding ~yaz is not exported as root:
$ sudo -u yaz ls ~yaz
To edit the _i_n_d_e_x_._h_t_m_l file as user www:
$ sudo -u www vi ~www/htdocs/index.html
To view system logs only accessible to root and users in the adm group:
$ sudo -g adm view /var/log/syslog
To run an editor as jim with a different primary group:
$ sudo -u jim -g audio vi ~jim/sound.txt
To shutdown a machine:
$ sudo shutdown -r +15 "quick reboot"
To make a usage listing of the directories in the /home partition.
Note that this runs the commands in a sub-shell to make the cd and file
redirection work.
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$ sudo sh -c "cd /home ; du -s * | sort -rn > USAGE"
_g_r_e_p(1), _s_u(1), _s_t_a_t(2), _l_o_g_i_n___c_a_p(3), _p_a_s_s_w_d(4), _s_u_d_o_e_r_s(5),
Many people have worked on ssuuddoo over the years; this version consists
of code written primarily by:
Todd C. Miller
See the HISTORY file in the ssuuddoo distribution or visit for a short history of ssuuddoo.
There is no easy way to prevent a user from gaining a root shell if
that user is allowed to run arbitrary commands via ssuuddoo. Also, many
programs (such as editors) allow the user to run commands via shell
escapes, thus avoiding ssuuddoo's checks. However, on most systems it is
possible to prevent shell escapes with ssuuddoo's _n_o_e_x_e_c functionality.
See the _s_u_d_o_e_r_s(4) manual for details.
It is not meaningful to run the cd command directly via sudo, e.g.,
$ sudo cd /usr/local/protected
since when the command exits the parent process (your shell) will still
be the same. Please see the EXAMPLES section for more information.
If users have sudo ALL there is nothing to prevent them from creating
their own program that gives them a root shell regardless of any '!'
elements in the user specification.
Running shell scripts via ssuuddoo can expose the same kernel bugs that
make setuid shell scripts unsafe on some operating systems (if your OS
has a /dev/fd/ directory, setuid shell scripts are generally safe).
If you feel you have found a bug in ssuuddoo, please submit a bug report at
Limited free support is available via the sudo-users mailing list, see to subscribe or search
the archives.
ssuuddoo is provided ``AS IS'' and any express or implied warranties,
including, but not limited to, the implied warranties of
merchantability and fitness for a particular purpose are disclaimed.
See the LICENSE file distributed with ssuuddoo or for complete details.
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