sudo 명령 사용에 대한 질문 입니다.

[user1@MYHP ~]$ sudo -u root /bin/echo 1 > /root/abc.txt
bash: /root/abc.txt: Permission denied

[root@MYHP ~]# ls -la
total 1020092
dr-xr-x---. 10 root root       4096 Sep 21 17:19 .
dr-xr-xr-x. 23 root root       4096 Sep  1 03:25 ..
-rw-r--r--.  1 root root          0 Sep 21 16:47 abc.txt

## Sudoers allows particular users to run various commands as
## the root user, without needing the root password.
##
## Examples are provided at the bottom of the file for collections
## of related commands, which can then be delegated out to particular
## users or groups.
##
## This file must be edited with the 'visudo' command.
 
## Host Aliases
## Groups of machines. You may prefer to use hostnames (perhaps using
## wildcards for entire domains) or IP addresses instead.
# Host_Alias     FILESERVERS = fs1, fs2
# Host_Alias     MAILSERVERS = smtp, smtp2
 
## User Aliases
## These aren't often necessary, as you can use regular groups
## (ie, from files, LDAP, NIS, etc) in this file - just use %groupname
## rather than USERALIAS
# User_Alias ADMINS = jsmith, mikem
 
 
## Command Aliases
## These are groups of related commands...
 
## Networking
# Cmnd_Alias NETWORKING = /sbin/route, /sbin/ifconfig, /bin/ping, /sbin/dhclient, /usr/bin/net, /sbin/iptables, /usr/bin/rfcomm, /usr/bin/wvdial, /sbin/iwconfig, /sbin/mii-tool
 
## Installation and management of software
# Cmnd_Alias SOFTWARE = /bin/rpm, /usr/bin/up2date, /usr/bin/yum
 
## Services
# Cmnd_Alias SERVICES = /sbin/service, /sbin/chkconfig
 
## Updating the locate database
# Cmnd_Alias LOCATE = /usr/bin/updatedb
 
## Storage
# Cmnd_Alias STORAGE = /sbin/fdisk, /sbin/sfdisk, /sbin/parted, /sbin/partprobe, /bin/mount, /bin/umount
 
## Delegating permissions
# Cmnd_Alias DELEGATING = /usr/sbin/visudo, /bin/chown, /bin/chmod, /bin/chgrp
 
## Processes
# Cmnd_Alias PROCESSES = /bin/nice, /bin/kill, /usr/bin/kill, /usr/bin/killall
 
## Drivers
# Cmnd_Alias DRIVERS = /sbin/modprobe
 
# Defaults specification
 
#
# Disable "ssh hostname sudo <cmd>", because it will show the password in clear. 
#         You have to run "ssh -t hostname sudo <cmd>".
#
Defaults    requiretty
 
Defaults    env_reset
Defaults    env_keep =  "COLORS DISPLAY HOSTNAME HISTSIZE INPUTRC KDEDIR LS_COLORS"
Defaults    env_keep += "MAIL PS1 PS2 QTDIR USERNAME LANG LC_ADDRESS LC_CTYPE"
Defaults    env_keep += "LC_COLLATE LC_IDENTIFICATION LC_MEASUREMENT LC_MESSAGES"
Defaults    env_keep += "LC_MONETARY LC_NAME LC_NUMERIC LC_PAPER LC_TELEPHONE"
Defaults    env_keep += "LC_TIME LC_ALL LANGUAGE LINGUAS _XKB_CHARSET XAUTHORITY"
 
Defaults    secure_path = /sbin:/bin:/usr/sbin:/usr/bin
 
## Next comes the main part: which users can run what software on
## which machines (the sudoers file can be shared between multiple
## systems).
## Syntax:
##
##      user    MACHINE=COMMANDS
##
## The COMMANDS section may have other options added to it.
##
## Allow root to run any commands anywhere
root    ALL=(ALL)       ALL
 
## Allows members of the 'sys' group to run networking, software,
## service management apps and more.
# %sys ALL = NETWORKING, SOFTWARE, SERVICES, STORAGE, DELEGATING, PROCESSES, LOCATE, DRIVERS
 
## Allows people in group wheel to run all commands
# %wheel        ALL=(ALL)       ALL
 
## Same thing without a password
# %wheel        ALL=(ALL)       NOPASSWD: ALL
 
## Allows members of the users group to mount and unmount the
## cdrom as root
# %users  ALL=/sbin/mount /mnt/cdrom, /sbin/umount /mnt/cdrom
 
## Allows members of the users group to shutdown this system
# %users  localhost=/sbin/shutdown -h now
 
## Read drop-in files from /etc/sudoers.d (the # here does not mean a comment)
#includedir /etc/sudoers.d
 
user1 ALL=(ALL)       NOPASSWD: ALL