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PASSWD(1) - User Commands

👤 NAME

passwd - change user password

🚀 Quick Reference

Use Case	Command	Description
Change own password	passwd	Prompts for old and new password.
Change another user's password (root)	passwd LOGIN	Superuser can change any account.
Lock a password	passwd -l LOGIN	Disables password by adding '!' to encrypted field.
Unlock a password	passwd -u LOGIN	Restores previous password value.
Delete a password	passwd -d LOGIN	Makes account passwordless.
Show account status	passwd -S [LOGIN]	Displays password state and aging info.
Expire password immediately	passwd -e LOGIN	Forces password change at next login.
Set password aging	passwd -n MIN -x MAX -w WARN -i INACTIVE LOGIN	Configure minimum, maximum, warning, and inactivity days.
Show all users’ status (root)	passwd -Sa	List status for all accounts (combines -S and -a).

🔧 SYNOPSIS

passwd [options] [LOGIN]

📖 DESCRIPTION

The passwd command changes passwords for user accounts. A normal user may only change the password for their own account, while the superuser may change the password for any account. passwd also changes the account or associated password validity period.

🔒 Password Changes

• 🔑 The user is first prompted for their old password, if one is present. This password is then encrypted and compared against the stored password. The user has only one chance to enter the correct password. The superuser is permitted to bypass this step so that forgotten passwords may be changed.
• ⏳ After the password has been entered, password aging information is checked to see if the user is permitted to change the password at this time. If not, passwd refuses to change the password and exits.
• 🔁 The user is then prompted twice for a replacement password. The second entry is compared against the first and both are required to match in order for the password to be changed.
• 🔐 Then, the password is tested for complexity. As a general guideline, passwords should consist of 6 to 8 characters including one or more characters from each of the following sets:
  • 🔤 lower case alphabetics
  • 🔢 digits 0 thru 9
  • 🔣 punctuation marks
  Care must be taken not to include the system default erase or kill characters. passwd will reject any password which is not suitably complex.

💡 Hints for user passwords

• 🔒 The security of a password depends upon the strength of the encryption algorithm and the size of the key space. The legacy UNIX System encryption method is based on the NBS DES algorithm. More recent methods are now recommended (see ENCRYPT_METHOD). The size of the key space depends upon the randomness of the password which is selected.
• ⚠️ Compromises in password security normally result from careless password selection or handling. For this reason, you should not select a password which appears in a dictionary or which must be written down. The password should also not be a proper name, your license number, birth date, or street address. Any of these may be used as guesses to violate system security.
• 🌐 You can find advice on how to choose a strong password on http://en.wikipedia.org/wiki/Password_strength

⚙️ OPTIONS

• -a, --all — 🔍 This option can be used only with -S and causes show status for all users.
• -d, --delete — 🗑️ Delete a user's password (make it empty). This is a quick way to disable a password for an account. It will set the named account passwordless.
• -e, --expire — ⏰ Immediately expire an account's password. This in effect can force a user to change their password at the user's next login.
• -h, --help — ❓ Display help message and exit.
• -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 INACTIVE days, the user may no longer sign on to the account.
• -k, --keep-tokens — 🔄 Indicate password change should be performed only for expired authentication tokens (passwords). The user wishes to keep their non-expired tokens as before.
• -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 adds a '!' at the beginning of the password).
  Note that this does not disable the account. The user may still be able to login using another authentication token (e.g. an SSH key). To disable the account, administrators should use usermod --expiredate 1 (this sets the account's expire date to 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 their password at any time.
• -q, --quiet — 🤫 Quiet mode.
• -r, --repository REPOSITORY — 🗂️ Change password in REPOSITORY repository.
• -R, --root CHROOT_DIR — 📁 Apply changes in the CHROOT_DIR directory and use the configuration files from the CHROOT_DIR directory.
• -S, --status — 📊 Display account status information. The status information consists of 7 fields. The first field is the user's login name. The second field indicates if the user account has a locked password (L), has no password (NP), or has a usable password (P). The third field gives the date of the last password change. The next four fields are the minimum age, maximum age, warning period, and inactivity period for the password. These ages are expressed in days.
• -u, --unlock — 🔓 Unlock the password of the named account. This option re-enables a password by changing the password back to its previous value (to the value before using the -l option).
• -w, --warndays WARN_DAYS — ⏳ Set the number of days of warning before a password change is required. The WARN_DAYS option 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 is required to be changed.
  Passing the number -1 as MAX_DAYS will remove checking a password's validity.

⚠️ CAVEATS

• 🔐 Password complexity checking may vary from site to site. The user is urged to select a password as complex as he or she feels comfortable with.
• 🌐 Users may not be able to change their password on a system if NIS is enabled and they are not logged into the NIS server.
• 🔧 passwd uses PAM to authenticate users and to change their passwords.

📁 FILES

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

🚪 EXIT VALUES

Exit Code	Meaning
0	✅ success
1	🚫 permission denied
2	❌ invalid combination of options
3	⚠️ unexpected failure, nothing done
4	📂 unexpected failure, passwd file missing
5	⏳ passwd file busy, try again
6	🔧 invalid argument to option

🔗 SEE ALSO

• chpasswd(8)
• passwd(5)
• shadow(5)
• usermod(8)

shadow-utils 4.8.1 02/06/2024

---

OPENSSL-CMDS(1SSL) - OpenSSL

👤 NAME

asn1parse, ca, ciphers, cms, crl, crl2pkcs7, dgst, dhparam, dsa, dsaparam, ec, ecparam, enc, engine, errstr, gendsa, genpkey, genrsa, info, kdf, mac, nseq, ocsp, passwd, pkcs12, pkcs7, pkcs8, pkey, pkeyparam, pkeyutl, prime, rand, rehash, req, rsa, rsautl, s_client, s_server, s_time, sess_id, smime, speed, spkac, srp, storeutl, ts, verify, version, x509 - OpenSSL application commands

🚀 Quick Reference

Use Case	Command	Description
Generate RSA key	openssl genrsa	Generate an RSA private key.
Generate CSR	openssl req	Generate a certificate signing request.
View certificate	openssl x509	Display certificate information.
Encrypt/decrypt data	openssl enc	Symmetric cipher commands.
Compute digest	openssl dgst	Message digest (hash) computation.
Test SSL connection	openssl s_client	Generic SSL/TLS client test.
List ciphers	openssl ciphers	Display available cipher suites.
OCSP	openssl ocsp	Online Certificate Status Protocol client.
PKCS#12	openssl pkcs12	PKCS#12 file (PFX) manipulation.
Version info	openssl version	Display OpenSSL version information.

🔧 SYNOPSIS

openssl cmd -help | [-option | -option arg] ... [arg] ...

📖 DESCRIPTION

Every cmd listed above is a (sub-)command of the openssl(1) application. It has its own detailed manual page at openssl-cmd(1). For example, to view the manual page for the openssl dgst command, type man openssl-dgst.

⚙️ OPTIONS

Among others, every subcommand has a help option.

• -help — ❓ Print out a usage message for the subcommand.

🔗 SEE ALSO

• openssl(1)
• openssl-asn1parse(1)
• openssl-ca(1)
• openssl-ciphers(1)
• openssl-cms(1)
• openssl-crl(1)
• openssl-crl2pkcs7(1)
• openssl-dgst(1)
• openssl-dhparam(1)
• openssl-dsa(1)
• openssl-dsaparam(1)
• openssl-ec(1)
• openssl-ecparam(1)
• openssl-enc(1)
• openssl-engine(1)
• openssl-errstr(1)
• openssl-gendsa(1)
• openssl-genpkey(1)
• openssl-genrsa(1)
• openssl-info(1)
• openssl-kdf(1)
• openssl-mac(1)
• openssl-nseq(1)
• openssl-ocsp(1)
• openssl-passwd(1)
• openssl-pkcs12(1)
• openssl-pkcs7(1)
• openssl-pkcs8(1)
• openssl-pkey(1)
• openssl-pkeyparam(1)
• openssl-pkeyutl(1)
• openssl-prime(1)
• openssl-rand(1)
• openssl-rehash(1)
• openssl-req(1)
• openssl-rsa(1)
• openssl-rsautl(1)
• openssl-s_client(1)
• openssl-s_server(1)
• openssl-s_time(1)
• openssl-sess_id(1)
• openssl-smime(1)
• openssl-speed(1)
• openssl-spkac(1)
• openssl-srp(1)
• openssl-storeutl(1)
• openssl-ts(1)
• openssl-verify(1)
• openssl-version(1)
• openssl-x509(1)

📜 HISTORY

Initially, the manual page entry for the "openssl cmd" command used to be available at cmd(1). Later, the alias openssl-cmd(1) was introduced, which made it easier to group the openssl commands using the apropos(1) command or the shell's tab completion.

In order to reduce cluttering of the global manual page namespace, the manual page entries without the 'openssl-' prefix have been deprecated in OpenSSL 3.0 and will be removed in OpenSSL 4.0.

©️ COPYRIGHT

Copyright 2019-2020 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the Apache License 2.0 (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at https://www.openssl.org/source/license.html.

3.0.2 2026-06-02

---

PASSWD(5) - File Formats and Conversions

👤 NAME

passwd - the password file

🚀 Quick Reference

Field #	Name	Description
1	login name	User's login name (unique)
2	encrypted password	Optional; 'x' means shadow; '!' means locked; empty means no password
3	numerical user ID	UID (0 for root)
4	numerical group ID	Primary GID
5	user name or comment field	Full name, office, etc.
6	user home directory	Initial working directory
7	optional user command interpreter	Shell (e.g., /bin/bash); default /bin/sh

📖 DESCRIPTION

/etc/passwd contains one line for each user account, with seven fields delimited by colons (":"). These fields are:

• 👤 login name
• 🔑 optional encrypted password
• 🔢 numerical user ID
• 👥 numerical group ID
• 📝 user name or comment field
• 🏠 user home directory
• 💻 optional user command interpreter

If the password field is a lower-case "x", then the encrypted password is actually stored in the shadow(5) file instead; there must be a corresponding line in the /etc/shadow file, or else the user account is invalid.

The encrypted password field may be empty, in which case no password is required to authenticate as the specified login name. However, some applications which read the /etc/passwd file may decide not to permit any access at all if the password field is blank.

A password field which starts with an exclamation mark means that the password is locked. The remaining characters on the line represent the password field before the password was locked.

Refer to crypt(3) for details on how this string is interpreted.

If the password field contains some string that is not a valid result of crypt(3), for instance ! or *, the user will not be able to use a unix password to log in (but the user may log in the system by other means).

The comment field is used by various system utilities, such as finger(1).

The home directory field provides the name of the initial working directory. The login program uses this information to set the value of the $HOME environmental variable.

The command interpreter field provides the name of the user's command language interpreter, or the name of the initial program to execute. The login program uses this information to set the value of the $SHELL environmental variable. If this field is empty, it defaults to the value /bin/sh.

📁 FILES

• /etc/passwd — User account information.
• /etc/shadow — optional encrypted password file
• /etc/passwd- — Backup file for /etc/passwd.
  Note that this file is used by the tools of the shadow toolsuite, but not by all user and password management tools.

🔗 SEE ALSO

• crypt(3)
• getent(1)
• getpwnam(3)
• login(1)
• passwd(1)
• pwck(8)
• pwconv(8)
• pwunconv(8)
• shadow(5)
• su(1)
• sulogin(8)

shadow-utils 4.8.1 02/06/2024

👤 NAME 🚀 Quick Reference 🔧 SYNOPSIS 📖 DESCRIPTION ⚙️ OPTIONS ⚠️ CAVEATS 📁 FILES 🚪 EXIT VALUES 🔗 SEE ALSO 👤 NAME 🚀 Quick Reference 🔧 SYNOPSIS 📖 DESCRIPTION ⚙️ OPTIONS 🔗 SEE ALSO 📜 HISTORY ©️ COPYRIGHT 👤 NAME 🚀 Quick Reference 📖 DESCRIPTION 📁 FILES 🔗 SEE ALSO