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Mansa Musa was the ruler of the Mali Empire in West Africa. Details recorded here should be sourced; unknown information is left blank.
MORE →Reflects the personal views, recollections, and perspective of the author, Mike Davis.
This is a personal recollection on the Move fire on May 13, 1985
| su | |
|---|---|
 | |
| Original authors | |
| Developer | AT&T Bell Laboratories |
| Release | November 3, 1971 |
| Operating system | Unix and Unix-like |
| Type | Command |
The Unix command su, which stands for "substitute user"[1][2] (or historically "superuser"[3][4]), is used by a computer user to execute commands with the privileges of another user account. When executed it invokes a shell without changing the current working directory or the user environment.
When the command is used without specifying the new user id as a command line argument, it defaults to using the superuser account (user id 0) of the system.
The command su, including the Unix permissions system and the setuid system call, was part of Version 1 Unix. Encrypted passwords appeared in Version 3.[5] The command is available as a separate package for Microsoft Windows as part of the UnxUtils collection of native Win32 ports of common GNU Unix-like utilities.[6]
When run from the command line, su asks for the target user's password, and if authenticated, grants the operator access to that account and the files and directories that account is permitted to access.
john@localhost:~$ su jane
Password:
jane@localhost:/home/john$ exit
logout
john@localhost:~$
When used with a hyphen (su -) it can be used to start a login shell. In this mode users can assume the user environment of the target user.
john@localhost:~$ su - jane
Password:
jane@localhost:~$
The command sudo is related, and executes a command as another user but observes a set of constraints about which users can execute which commands as which other users (generally in a configuration file named /etc/sudoers, best editable by the command visudo). Unlike su, sudo authenticates users against their own password rather than that of the target user (to allow the delegation of specific commands to specific users on specific hosts without sharing passwords among them and while mitigating the risk of any unattended terminals).
Some Unix-like systems implement the user group wheel, and only allow members to become root with su.[7] This may or may not mitigate these security concerns, since an intruder might first simply break into one of those accounts. GNU su, however, does not support the group wheel for philosophical reasons. Richard Stallman argues that because the group would prevent users from utilizing root passwords leaked to them, the group would allow existing admins to ride roughshod over ordinary users.[8]
su - run a command with substitute user and group ID
su - substitute user id temporarily
su -- become privileged user... su allows one to become the super-user.
su: become super-user
| File system | |
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| Processes | |
| User environment | |
| Text processing | |
| Shell builtins | |
| Searching | |
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 | This Unix-related article is a stub. You can help Wikipedia by adding missing information. |
Source: Wikipedia. Article content is retrieved live through the MediaWiki API.
The Unix command su, which stands for "substitute user" (or historically "superuser"), is used by a computer user to execute commands with the privileges of another user account. When executed it invokes a shell without changing the current working directory or the user environment. When the command is used without specifying the new user id as a command line argument, it defaults to using the superuser account (user id 0) of the system.
sudo ( or ) is a shell command on Unix-like operating systems that enables a user to run a program with the security privileges of another user, by default the superuser. It originally stood for "superuser do", as that was all it did, and this remains its most common usage; however, the official Sudo project page lists it as "su 'do'". The current Linux manual pages define su as "substitute user", making the modern meaning of sudo "substitute user, do", because sudo can run a command as other users as well. Unlike the similar command su, users must, by default, supply their own password for authentication, rather than the password of the target user. After authentication, and if the configuration file (typically /etc/sudoers) permits the user access, the system invokes the requested command. The configuration file offers detailed access permissions, including enabling commands only from the invoking terminal; requiring a password per user or group; requiring re-entry of a password every time or never requiring a password at all for a particular command line. It can also be configured to permit passing arguments or multiple commands.
In computing, runas (a compound word, from “run as”) is a command in the Microsoft Windows line of operating systems that allows a user to run specific tools and programs under a different username to the one that was used to logon to a computer interactively. It is similar to the Unix commands sudo and su, but the Unix commands generally require prior configuration by the system administrator to work for a particular user and/or command.
tr is a command in Unix, Plan 9, Inferno, and Unix-like operating systems. It is an abbreviation of translate or transliterate, indicating its operation of replacing or removing specific characters in its input data set.
Before the 1921 destruction of Tulsa’s Greenwood District, Black residents had created a remarkable center of business and community life. The district included stores, professional offices, entertainment venues and homes owned by Black citizens. Understanding Greenwood means learning what was built—not only what was burned.
MORE →Mae Jemison, aboard Space Shuttle Endeavour in 1992.
