passwd (用于更改用戶帳戶的密碼)

瑞茲發(fā)表于 2020-11-03 09:39

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命令行 Unix&Linux命令 passwd

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在類似Unix的操作系統(tǒng)上，passwd命令用于更改用戶帳戶的密碼。

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1 passwd 運行系統(tǒng)環(huán)境

2 passwd 描述

3 passwd 語法

4 passwd 例子

passwd 運行系統(tǒng)環(huán)境

Linux

passwd 描述

本文檔介紹了passwd的Linux版本。

passwd命令更改為密碼的用戶帳戶。普通用戶只能更改自己帳戶的密碼，而超級用戶可以更改任何帳戶的密碼。passwd還可以更改或重置帳戶的有效期-密碼過期之前必須經(jīng)過多少時間，必須更改密碼。

普通用戶必須先輸入當(dāng)前密碼進(jìn)行驗證，然后才能更改自己的密碼。（超級用戶可以在更改其他用戶的密碼時跳過此步驟。）

在驗證了當(dāng)前密碼后，passwd會檢查此時是否允許用戶更改密碼。如果不是，則passwd拒絕繼續(xù)，然后退出。

否則，然后兩次提示用戶輸入替換密碼。這兩個條目必須匹配才能使passwd繼續(xù)。

接下來，測試密碼的復(fù)雜性。作為一般準(zhǔn)則，密碼應(yīng)至少包含6個字符，包括以下每個或多個：

小寫字母
數(shù)字0到9
標(biāo)點符號

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passwd 語法

passwd [OPTION] [USER]

選件

以下選項將更改passwd的操作方式：

-a，--all	當(dāng)與-S一起使用（見下文）時，此選項將顯示所有用戶的密碼狀態(tài)。如果不使用-S，則此選項將不起作用。
-d，-delete	刪除用戶的密碼（使其為空）。此選項是一種禁用帳戶登錄而又不禁用帳戶本身的快速方法。
-e，-- expire	立即使帳戶密碼失效。這將迫使用戶在下次登錄時更改其密碼。
-h，--help	顯示有關(guān)如何使用passwd命令的信息。
-i，-- inactive INACTIVE	此選項用于在密碼過期數(shù)天后禁用帳戶。用戶帳戶的密碼過期了無效的整數(shù)天后，該用戶可能不再登錄該帳戶。
-k，-- keep-tokens	保留密碼令牌。指示該用戶的密碼僅在過期后才可以更改。
-l，--lock	鎖定命名帳戶的密碼。此選項通過將密碼更改為與可能的加密值不匹配的值來禁用密碼。它通過在加密密碼的開頭添加一個字符來實現(xiàn)。請注意，這不會禁用該帳戶。用戶可能仍然可以使用其他身份驗證方法（例如SSH密鑰）登錄。要禁用該帳戶，超級用戶可以將usermod命令與--expiredate 1選項一起使用。此選項會將帳戶的到期日期設(shè)置為過去的日期，即1970年1月2日。密碼鎖定的用戶不允許更改密碼。
-n，-- mindays MIN_DAYS	將兩次密碼更改之間的最短天數(shù)設(shè)置為MIN_DAYS。該字段的值為零表示用戶可以隨時更改其密碼。
-q，-quiet	靜音模式; passwd將在不顯示任何輸出的情況下運行。
-R，--root CHROOT_DIR	對于高級用戶：此選項將在chroot目錄CHROOT_DIR中應(yīng)用更改，并使用CHROOT_DIR目錄中的配置文件。
-S，--status	顯示帳戶狀態(tài)信息。狀態(tài)信息包含7個字段：用戶的登錄名密碼可用性：如果帳戶具有鎖定密碼，則為L；如果帳戶沒有密碼，則為NP；如果帳戶具有可用的密碼，則為P 上次密碼更改的日期最低密碼年齡密碼最長使用期限密碼警告期密碼無效期在字段4到7中，密碼期限以天為單位。除了-S以外，還指定-a將顯示所有用戶的密碼狀態(tài)。
-u，--unlock	解鎖指定帳戶的密碼。在使用-l選項鎖定密碼之前，此選項通過將密碼改回其值來重新啟用密碼。
-w，-- warndays WARN_DAYS	設(shè)置需要更改密碼之前的警告天數(shù)。WARN_DAYS是密碼到期之前的天數(shù)，系統(tǒng)將警告用戶密碼即將過期。
-x，-- maxdays MAX_DAYS	設(shè)置密碼有效的最大天數(shù)。MAX_DAYS之后，必須更改密碼。

筆記

密碼復(fù)雜度將因系統(tǒng)而異。有關(guān)默認(rèn)復(fù)雜性規(guī)則以及如何更改規(guī)則，請查閱您的操作系統(tǒng)文檔。

在使用NIS（網(wǎng)絡(luò)信息服務(wù)）的系統(tǒng)上，如果用戶未登錄NIS服務(wù)器，則可能無法更改其密碼。

passwd使用的文件

/ etc / passwd	用戶帳戶信息。
/ etc /shadow	安全的用戶帳戶信息。
/etc/pam.d/passwd	passwd的PAM配置。

passwd [OPTION] [USER]

Options

The following options will change the way passwd operates:

-a, --all	When used with -S (see below), this option will show the password status for all users. This option will not work if used without -S.
-d, --delete	Delete a user's password (make it empty). This option is a quick way to disable logins for an account, without disabling the account itself.
-e, --expire	Immediately expire an account's password. This forces a user to change their password the next time they log in.
-h, --help	Display information about how to use the passwd command.
-i, --inactive INACTIVE	This option is used to disable an account after the password has been expired for a number of days. After a user account has had an expired password for integer INACTIVE days, the user may no longer sign on to the account.
-k, --keep-tokens	Keep password tokens. Indicates that this user's password should only be changed if it has expired.
-l, --lock	Lock the password of the named account. This option disables a password by changing it to a value which matches no possible encrypted value. It does this by adding a character at the beginning of the encrypted password. Note that this does not disable the account. The user may still be able to log in using another authentication method (an SSH key, for example). To disable the account, the superuser can use the usermod command with the option --expiredate 1. This option will set the account's expiration date to a date in the past — namely Jan 2, 1970. Users with a locked password are not allowed to change their password.
-n, --mindays MIN_DAYS	Set the minimum number of days between password changes to MIN_DAYS. A value of zero for this field indicates that the user may change his/her password at any time.
-q, --quiet	Quiet mode; passwd will operate without displaying any output.
-R, --root CHROOT_DIR	For advanced users: this option will apply changes in the chroot directory CHROOT_DIR and use the configuration files from the CHROOT_DIR directory.
-S, --status	Display account status information. The status information consists of 7 fields: The user's login name password usability: L if the account has a locked password,NP if the account has no password, or P if the account has a usable password date of the last password change minimum password age maximum password age password warning period password inactivity period In fields 4 through 7,password ages are expressed in days. Specifying -a in addition to -S displays password status for all users.
-u, --unlock	Unlock the password of the named account. This option re-enables a password by changing the password back to its value before the -l option was used to lock it.
-w, --warndays WARN_DAYS	Set the number of days of warning before a password change is required. WARN_DAYS is the number of days prior to the password expiring that a user will be warned that their password is about to expire.
-x, --maxdays MAX_DAYS	Set the maximum number of days a password remains valid. After MAX_DAYS, the password must be changed.

Notes

Password complexity will vary depending on the system. Consult your operating system documentation for default complexity rules and how to change them.

On systems that use NIS (Network Information Services), users may not be able to change their password if they are not logged into the NIS server.

Files used by passwd

/etc/passwd	User account information.
/etc/shadow	Secure user account information.
/etc/pam.d/passwd	PAM configuration for passwd.

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passwd 例子

更改您的密碼

passwd

運行不帶任何選項的passwd將更改運行命令的帳戶的密碼。首先將提示您輸入帳戶的當(dāng)前密碼：

(current) UNIX password:

如果正確，則將要求您輸入新密碼：

Enter new UNIX password:

...并再次輸入相同的密碼以進(jìn)行驗證：

Retype new UNIX password:

如果密碼匹配，密碼將被更改。

更改其他用戶的密碼

sudo passwd jeff

如果您具有超級用戶特權(quán)，則可以更改其他用戶的密碼。在這里，我們?yōu)槊罴由?b>sudo前綴，以超級用戶身份運行它。此命令將更改用戶jeff的密碼。不會提示您輸入jeff的當(dāng)前密碼。

在不知道當(dāng)前密碼的情況下更改密碼

如果由于忘記了密碼而需要更改密碼，則需要登錄到root帳戶。為此，您將需要知道root用戶的密碼。

假設(shè)您的用戶名是sally，并且您忘記了密碼。但是，您具有系統(tǒng)管理員權(quán)限：您可以使用該帳戶的密碼以root用戶身份登錄。以root用戶身份登錄，然后從命令行運行：

passwd sally

但是，如果您也忘記了root的密碼怎么辦？在這種情況下，您將需要以單用戶模式（也稱為運行級別1）登錄到計算機(jī)。無法通過網(wǎng)絡(luò)完成此操作，因此您將需要對計算機(jī)的物理訪問權(quán)才能啟動到此運行級別。

重新啟動機(jī)器。在啟動時，應(yīng)該顯示一個引導(dǎo)程序菜單。在許多系統(tǒng)上，例如Debian或Ubuntu，啟動菜單將包含“恢復(fù)模式”或“單用戶模式”的選項（如下圖所示）。選擇此啟動選項。

此選項將引導(dǎo)您進(jìn)入純文本模式，并以root用戶身份登錄。

如果需要掛載 /，請執(zhí)行以下操作：

mount -rw -o remount /

現(xiàn)在更改sally的密碼：

passwd sally

或root：

passwd

完成后，重新啟動系統(tǒng)：

shutdown -r now

正常啟動系統(tǒng)，您應(yīng)該可以使用新密碼以sally身份登錄。

其他例子

sudo passwd -S ted

檢查名為ted的用戶的密碼狀態(tài)。輸出將類似于以下內(nèi)容：

ted P 05/13/2014 2 365 7 28

在這里，我們看到用戶的名稱（ted），后跟一個P，指示該用戶的密碼當(dāng)前有效且可用。該密碼將于2014年5月5日到期。Ted最多只能每2天更改一次密碼，而必須每365天更改一次密碼。將在要求更改密碼的7天前警告他，如果他允許密碼過期，則28天后將禁用其帳戶。

sudo passwd -S -a

與上面的命令類似，但是在系統(tǒng)范圍內(nèi)檢查所有用戶帳戶的密碼狀態(tài)。

sudo passwd -l jane

鎖定用戶jane的密碼。在系統(tǒng)管理員將其解鎖之前，她將無法登錄。

sudo passwd -u jane

解鎖jane的密碼。它將自動重置為鎖定之前的狀態(tài)，她將能夠再次登錄。

sudo passwd -e alan

使alan的密碼過期。下次登錄時，將要求他設(shè)置一個新密碼。

Change your password

passwd

Running passwd with no options will change the password of the account running the command. You will first be prompted to enter the account's current password:

(current) UNIX password:

If it is correct, you will then be asked to enter a new password:

Enter new UNIX password:

...and to enter the same password again, to verify it:

Retype new UNIX password:

If the passwords match, the password will be changed.

Change another user's password

sudo passwd jeff

If you have superuser privileges, you can change another user's password. Here, we prefix the command with sudo to run it as the superuser. This command will change the password for user jeff. You will not be prompted for jeff's current password.

Change your password without knowing your current password

If you need to change your password because you forgot it, you will need to log in to the root account. To do this, you will need to know the password for user root.

Let's say your username is sally, and you can't remember your password. However, you have administrator access to the system: you can log in as root, using the password for that account. Log in as root, and then from the command line, run:

passwd sally

But what if you forgot the password for root as well? In this case, you will need to log in to the machine in single-user mode, also known as Runlevel 1. This cannot be done over the network, so you will need physical access to the machine to boot into this runlevel.

Reboot the machine. When it is booting up, you should be presented with a bootloader menu. On many systems, such as Debian or Ubuntu, the boot menu will include an option for "Recovery Mode" or "Single User Mode" (as in the image below). Select this boot option.

This option will boot you into a text-only mode, and log you in as root.

If you need to mount /, do so:

mount -rw -o remount /

Now change sally's password:

passwd sally

Or root's:

passwd

When you're done, reboot your system:

shutdown -r now

Start the system normally, and you should be able to log in as sally with the new password.

Additional examples

sudo passwd -S ted

Check the status of the password for the user named ted. Output will resemble the following:

ted P 05/13/2014 2 365 7 28

Here, we see the user's name (ted), followed by a P, indicating that his password is currently valid and usable. The password will expire on May 5, 2014. Ted cannot change his password more often than every 2 days, and must change the password every 365 days. He will be warned 7 days before a required password change, and if he allows his password to expire, his account will be disabled 28 days later.

sudo passwd -S -a

Similar to the above command, but checks the password status for all user accounts, system-wide.

sudo passwd -l jane

Lock the password for user jane. She will be unable to log in until a system administrator unlocks it.

sudo passwd -u jane

Unlock jane's password. It will automatically be reset to whatever it was before it was locked, and she will be able to log in again.

sudo passwd -e alan

Expire alan's password. The next time he logs in, he will be required to set a new password.

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其他命令行

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