linuxsudoi

A. linux裡面root登錄和sudo -i區別是什麼

root用戶表示直接擁有最大權，可以不加任何條件執行任何操作，從便利程度上來說是很便利的；
sudo -i：為了頻繁的執行某些只有超級用戶才能執行的許可權，而不用每次輸入密碼，可以使用該命令；提示輸入密碼時該密碼為當前賬戶的密碼，沒有時間限制，執行該命令後提示符變為「#」而不是「$」，想退回普通賬戶時可以執行「exit」或「logout」 ；
從安全層面上來說，直接使用root是很不安全的，不小心就會被 "rm -rf", 反而，使用sudo -i ，這樣更安全一些,至少不能直接使用命令刪除一些重要的文件和進程等；

B. linux下面的sudo命令什麼意思

sudo 表示 「superuser do」。 它允許已驗證的用戶以其他用戶的身份來運行命令。其他用戶可版以是普通權用戶或者超級用戶。然而，大部分時候我們用它來以提升的許可權來運行命令。

apt 是Linux下的一款安裝包管理工具，是一個客戶/伺服器系統。sudo apt-get是用來安裝linux下的各種工具包的。

(2)linuxsudoi擴展閱讀：

注意事項：

編輯sudo的配置文件/etc/sudoers是一般不要直接使用vi（vi /etc/sudoers）去編輯，因為sudoers配置有一定的語法，直接用vi編輯保存系統不會檢查語法，如有錯也保存了可能導致無法使用sudo工具，而使用visudo命令去配置保存時會進行語法檢查，有錯會有提示。

命令一定要使用絕對路徑，避免其他目錄的同名命令被執行，造成安全隱患 ，因此使用的時候也是使用絕對路徑！

C. 在linux操作系統中怎樣讀取u盤

1、首先需要把U盤插入Linux電腦，確保U盤指示燈是亮著的進入Linux系統主界面，按Ctrl+Alt+T打開命令窗口。

D. sudo -i和sudo -s有什麼區別

sudo -i：

Linux終端命令下改變用戶對命令使用許可權的命令。
sudo-s ：

執行環境變數中的 SHELL 所指定的 shell ，或是 /etc/passwd 里所指定的 shell 。

E. Linux下的命令sudo怎麼讀

類似拼音的的讀法：su do或者xiu do，這樣的讀法，詳細單詞是superuserdo，意為超級管理員可以做的動作。

F. 在linux操作系統中怎樣讀取u盤為啥我的linux操作系

1、首先需要把U盤插入Linux電腦，確保U盤指示燈是亮著的進入Linux系統主界面，按Ctrl+Alt+T打開命令窗口。

2、先獲取高級用戶許可權，輸入命令:sudo -i，確定後輸入高級用戶密碼。

3、首先使用fdisk -l命令查看一下U盤是否有被識別到，及識別的U盤是在哪個位置，本次接入看到U盤的位置是/dev/Sdb4。

4、輸入掛載U盤命令：mount /dev/sdb4 /mnt，回車後即掛載U盤成功。

5、繼續輸入：cd 回車，可以查看U盤下的文件。

利用WinPE工具可以通過U盤來安裝Linux系統，下面以U盤WinPE工具安裝Centos6.4版Linux為例，方法如下：
1.在U盤上安裝好WinPE（可以選擇老毛桃U盤工具、大白菜PE等）
2.在U盤根目錄建立一個名為LMT的目錄，將CentOS-6.4-x86_64-minimal.iso鏡像拷入U盤下的LMT目錄。
3.將U盤插入電腦。重啟電腦，進入BIOS選擇U盤啟動，F10保存退出。
4.系統從U盤啟動以後顯示出老毛桃的啟動菜單。
5.菜單中有一項「啟動自定義ISO/IMG文件（LMT目錄）」，選擇該項。

6.系統會列出LMT目錄中的ISO文件，直接輸入對應的序號就可以安裝了。

首先，你的linux具體是什麼發行版？還有，你的u盤使用什麼格式？再有，你有沒有執行mount掛載？這些都有可能會影響u盤的顯示。
早期的linux，特別是紅帽企業版的第4版，第5版(RedHat Enterprise Linux 4、RedHat Enterprise Linux 5，通常習慣縮寫RHEL4、RHEL5)，不僅要執行mount -t 命令才能掛載。而且對於NTFS格式的磁碟，還要編譯安裝ntfs-3g。而對於linux本身支持的ext2,ext3以及windows下比較傳統的fat32則默認支持。當時的centos，fedora等基於紅帽的linux也是如此。
現在的一些發行版，特別是主要面對桌面用戶的，例如ubuntu，fedora，往往是在安裝完系統後，就能識別各種類型的磁碟分區的。不論它是fat32還是ntfs。當然了，linux的ext2、ext3、ext4、xfs肯定也是支持的。但是一些主要是面對服務的，例如RHEL6、RHEL7、CentOS6、CentOS7等等，往往默認的安裝系統時，就沒有安裝關於識別NTFS的軟體包。需要用戶自己去安裝。但是這個安裝已經比較方便了。前面說的RHEL4、RHEL5的時代，ntfs-3g只能用編譯安裝。而現在RHEL或CentOS6或7的時代，ntfs-3g已經有了rpm包，並添加進了yum軟體源裡面了，這意味著安裝它已經不想以前那麼麻煩了。
]$ yum list | grep ntfs
ntfs-3g.x86_64 2:2016.2.22-3.el6 @epel
ntfs-3g.i686 2:2016.2.22-3.el6 epel
ntfs-3g-devel.i686 2:2016.2.22-3.el6 epel
ntfs-3g-devel.x86_64 2:2016.2.22-3.el6 epel
ntfsprogs.i686 2.0.0-13.el6 epel
ntfsprogs.x86_64 2:2016.2.22-3.el6 epel
ntfsprogs-devel.i686 2.0.0-13.el6 epel
ntfsprogs-devel.x86_64 2.0.0-13.el6 epel
ntfsprogs-gnomevfs.x86_64 2.0.0-13.el6 epel

從這些可以看出，只要用戶配置好了epel源，就能裝ntfs-3g。裝好了，那麼使用ntfs格式的磁碟，分區等就能識別了。

此外，現在的linux版本中各種格式的分區，只要能識別就能自動掛載。屬於即插即用了。

G. 如何手動釋放Linux內存的方法

1、首先打開Linux命令窗口，可使用快捷鍵Ctrl+Alt+T打開。

H. linux系統如何把u盤中的文件復制過來

linux系統要把u盤中的文件復制過來需要先把U盤掛載到系統中的某一個位置，然後版再使用cp命令完權成拷貝。可以參考以下操作步驟：

1、把U盤插入Linux電腦，確保U盤指示燈是亮著的。進入Linux系統主界面，按Ctrl+Alt+T打開命令窗口，先獲取高級用戶許可權，輸入命令:sudo -i，確定後輸入高級用戶密碼

I. Linux操作系統下Sudo命令的使用方法

建議：
在Linux系統下，右鍵打開終端後，可以輸入"man sudo"或者"info sudo"查詢，因為使用方法實在是太多，可以摘要如下，其他可以自己查看。
NAME
sudo, sudoedit - execute a command as another user

SYNOPSIS
sudo -h | -K | -k | -L | -l | -V | -v

sudo [-bEHPS] [-p prompt] [-u username|#uid] [VAR=value]
{-i | -s | command}

sudoedit [-S] [-p prompt] [-u username|#uid] file ...

OPTIONS
sudo accepts the following command line options:

-b The -b (background) option tells sudo to run the given command in
the background. Note that if you use the -b option you cannot use
shell job control to manipulate the process.

-E The -E (preserve environment) option will override the env_reset
option in sudoers(5)). It is only available when either the
matching command has the SETENV tag or the setenv option is set in
sudoers(5).

-e The -e (edit) 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 sudoers file. If
the user is authorized by sudoers 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 VISUAL or EDITOR environment vari-
ables is run to edit the temporary files. If neither VISUAL
nor EDITOR are set, the program listed in the editor sudoers
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 sudo, the editor is run with the
invoking user's environment unmodified. If, for some reason, sudo
is unable to update a file with its edited version, the user will
receive a warning and the edited will remain in a temporary
file.

-H The -H (HOME) option sets the HOME environment variable to the
homedir of the target user (root by default) as specified in
passwd(5). By default, sudo does not modify HOME (see set_home and
always_set_home in sudoers(5)).

-h The -h (help) option causes sudo to print a usage message and exit.

-i The -i (simulate initial login) option runs the shell specified in
the passwd(5) entry of the user that the command is being run as.
The command name argument given to the shell begins with a '-' to
tell the shell to run as a login shell. sudo attempts to change to
that user's home directory before running the shell. It also ini-
tializes the environment, leaving TERM unchanged, setting HOME,
SHELL, USER, LOGNAME, and PATH, and unsetting all other environment
variables. Note that because the shell to use is determined before
the sudoers file is parsed, a runas_default setting in sudoers will
specify the user to run the shell as but will not affect which
shell is actually run.

-K The -K (sure kill) option is like -k except that it removes the
user's timestamp entirely. Like -k, this option does not require a
password.

-k The -k (kill) option to sudo invalidates the user's timestamp by
setting the time on it to the Epoch. The next time sudo is run a
password will be required. This option does not require a password
and was added to allow a user to revoke sudo permissions from a
.logout file.

-L The -L (list defaults) option will list out the parameters that may
be set in a Defaults line along with a short description for each.
This option is useful in conjunction with grep(1).

-l The -l (list) option will list out the allowed (and forbidden) com-
mands for the invoking user on the current host.

-P The -P (preserve group vector) option causes sudo to preserve the
invoking user's group vector unaltered. By default, sudo will ini-
tialize 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 The -p (prompt) 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 hostname including the domain name (on if
the machine's hostname is fully qualified or the fqdn sudoers
option is set)

%h expanded to the local hostname without the domain name

%p expanded to the user whose password is being asked for
(respects the rootpw, targetpw and runaspw flags in sudoers)

%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

-S The -S (stdin) option causes sudo to read the password from the
standard input instead of the terminal device.

-s The -s (shell) option runs the shell specified by the SHELL envi-
ronment variable if it is set or the shell as specified in
passwd(5).

-u The -u (user) option causes sudo to run the specified command as a
user other than root. To specify a uid instead of a username, use
#uid. When running commands as a uid, many shells require that the
'#' be escaped with a backslash ('\'). Note that if the targetpw
Defaults option is set (see sudoers(5)) it is not possible to run
commands with a uid not listed in the password database.
-V The -V (version) option causes sudo to print the version number and
exit. If the invoking user is already root the -V option will
print out a list of the defaults sudo was compiled with as well as
the machine's local network addresses.

-v If given the -v (validate) option, sudo will update the user's
timestamp, prompting for the user's password if necessary. This
extends the sudo timeout for another 5 minutes (or whatever the
timeout is set to in sudoers) but does not run a command.

-- The -- flag indicates that sudo should stop processing command line
arguments. It is most useful in conjunction with the -s flag.

Environment variables to be set for the command may also be passed on
the command line in the form of VAR=value, e.g.
LD_LIBRARY_PATH=/usr/local/pkg/lib. Variables passed on the command
line are subject to the same restrictions as normal environment vari-
ables with one important exception. If the setenv option is set in
sudoers, 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 for-
bidden. See sudoers(5) for more information.

J. Linux裡面sudo -i命令作用是什麼

顯示當前使用這個命令的賬戶擁有的許可權