describe
Passwd command sets and changes user passwords. Use this command to change the password of yourself or other users. You can also use the passwd command to change the full name (gecos) associated with the login name and the shell used as the operating system interface.
According to the user's definition, the user's password can exist locally or remotely. The local password exists in the /etc/security/passwd database. The remote password exists in the database of Network Information Service (NIS) or Distributed Computing Environment (DCE).
To change the password, enter the passwd command. The passwd command prompts the non-root user to enter the old password (if it exists), and then prompts the new password twice. (The password will not be displayed on the screen. If the two new passwords don't match, the passwd command will prompt you to re-enter the new password.
Extended data
Cryptographic synthesis
Password is a symbol compiled according to a specific law, which is used to transmit the information of both parties. In other words, a password is a series of symbols that hide the real content. It changes the information expressed by an open and standard information code into an information code that can't be read by anyone except the two communication parties through a transformation method. This unique information code is a password.
Cryptography is a science with a long history. In the war between ancient Greece and the Persian Empire, passwords were used to transmit secret information. In modern wars, the transmission of information and the command of war are inseparable from passwords, and so is the diplomatic struggle. Passwords are generally used for the confidentiality of information communication transmission and storage.
With the development of computer and information technology, the development of cryptography is also very rapid, and its application field is also expanding. Passwords are not only used for information encryption, but also for data information signature and security authentication. In this way, the application of cryptography is no longer limited to serving military and diplomatic struggles, but is widely used in social and economic activities.
Nowadays, there has been a trend of socialization and personalization of password application in the world. For example, cryptographic technology can be applied to e-commerce to identify the identities and commercial credits of both parties in online transactions and prevent "hackers" and fraud in online e-commerce.
When it is applied to VAT invoices, it can prevent forgery and tampering, put an end to all kinds of acts of stealing, leaking, escaping and defrauding state taxes by using VAT invoices, and greatly facilitate tax inspection; When it is applied to the identification of bank checks, it can greatly reduce the financial crime of financial fraud by using fake checks; When applied to personal mobile communication, it greatly enhances the confidentiality of communication information and so on.
According to Reuters, a batch of documents declassified by the British Security Service showed the work of British intelligence services to the world for the first time. Deciphering the "code in the skirt" is one of the famous ones.
Baidu encyclopedia-password
Baidu encyclopedia-password