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Nobody (username)
{{lowercase In many Unix variants, "nobody" is the conventional name of a user identifier which owns no files, is in no privileged groups, and has no abilities except those which every other user has. It is normally not enabled as a user account, i.e. has no home directory or login credentials assigned. Some systems also define an equivalent group "nogroup". Uses * The pseudo-user "nobody" and group "nogroup" are used, for example, in the NFSv4 implementation of Linux by idmapd, if a user or group name in an incoming packet does not match any known username on the system. * It was once common to run daemons as ''nobody'', especially on servers, in order to limit the damage that could be done by a malicious user who gained control of them. However, the usefulness of this technique is reduced if more than one daemon is run like this, because then gaining control of one daemon would provide control of them all. The reason is that processes owned by the same user have the ability t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unix
Unix (, ; trademarked as UNIX) is a family of multitasking, multi-user computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, and others. Initially intended for use inside the Bell System, AT&T licensed Unix to outside parties in the late 1970s, leading to a variety of both academic and commercial Unix variants from vendors including University of California, Berkeley ( BSD), Microsoft (Xenix), Sun Microsystems ( SunOS/ Solaris), HP/ HPE ( HP-UX), and IBM ( AIX). The early versions of Unix—which are retrospectively referred to as " Research Unix"—ran on computers such as the PDP-11 and VAX; Unix was commonly used on minicomputers and mainframes from the 1970s onwards. It distinguished itself from its predecessors as the first portable operating system: almost the entire operating system is written in the C programming language (in 1973), which allows U ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
User Identifier
Unix-like operating systems identify a user by a value called a user identifier, often abbreviated to user ID or UID. The UID, along with the group identifier (GID) and other access control criteria, is used to determine which system resources a user can access. The Passwd (file), password file maps textual user names to UIDs. UIDs are stored in the inodes of the Unix file system, running processes, tar archives, and the now-obsolete Network Information Service. In POSIX-compliant environments, the shell command id gives the current user's UID, as well as more information such as the user name, primary user group and group identifier (GID). Process attributes The POSIX standard introduced three different UID fields into the process descriptor table, to allow privileged processes to take on different roles dynamically: Effective user ID The effective UID (euid) of a process is used for most access checks. It is also used as the owner for files created by that process. The effectiv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
User Account
A user is a person who uses a computer or network service. A user often has a user account and is identified to the system by a username (or user name). Some software products provide services to other systems and have no direct end users. End user End users are the ultimate human users (also referred to as operators) of a software product. The end user stands in contrast to users who support or maintain the product such as sysops, database administrators and computer technicians. The term is used to abstract and distinguish those who only use the software from the developers of the system, who enhance the software for end users. In user-centered design, it also distinguishes the software operator from the client who pays for its development and other stakeholders who may not directly use the software, but help establish its requirements. This abstraction is primarily useful in designing the user interface, and refers to a relevant subset of characteristics that m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Home Directory
A home directory is a directory (file systems), file system directory on a multi-user operating system containing computer file, files for a given user (computing), user of the system. The specifics of the home directory (such as its name and location) are defined by the operating system involved; for example, Linux / BSD (Filesystem Hierarchy Standard, FHS) systems use /home/ or /usr/home/, macOS uses /Users/, and Microsoft Windows, Windows systems since Windows Vista use \Users\. Description A user's home directory is intended to contain that user's files; including text documents, music, pictures, videos, etc. It may also include their configuration files of preferred settings for any software they have used there and might have tailored to their liking: web browser bookmark (digital), bookmarks, favorite desktop metaphor, desktop wallpaper (computing), wallpaper and theme (computing), themes, stored passwords to any external services accessed via a given software, etc. The use ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Credentials
A credential is a piece of any document that details a qualification, competence, or authority issued to an individual by a third party with a relevant or '' de facto'' authority or assumed competence to do so. Examples of credentials include academic diplomas, academic degrees, certifications, security clearances, identification documents, badges, passwords, user names, keys, powers of attorney, and so on. Sometimes publications, such as scientific papers or books, may be viewed as similar to credentials by some people, especially if the publication was peer reviewed or made in a well-known journal or reputable publisher. Types and documentation of credentials A person holding a credential is usually given documentation or secret knowledge (''e.g.,'' a password or key) as proof of the credential. Sometimes this proof (or a copy of it) is held by a third, trusted party. While in some cases a credential may be as simple as a paper membership card, in other cases, such as di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NFSv4
Network File System (NFS) is a distributed file system protocol originally developed by Sun Microsystems (Sun) in 1984, allowing a user on a client computer to access files over a computer network much like local storage is accessed. NFS, like many other protocols, builds on the Open Network Computing Remote Procedure Call (ONC RPC) system. NFS is an open IETF standard defined in a Request for Comments (RFC), allowing anyone to implement the protocol. Versions and variations Sun used version 1 only for in-house experimental purposes. When the development team added substantial changes to NFS version 1 and released it outside of Sun, they decided to release the new version as v2, so that version interoperation and RPC version fallback could be tested. NFSv2 Version 2 of the protocol (defined in , March 1989) originally operated only over User Datagram Protocol (UDP). Its designers meant to keep the server side stateless, with locking (for example) implement ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Daemon (computing)
In computing, a daemon is a program that runs as a background process, rather than being under the direct control of an interactive user. Customary convention is to name a daemon process with the letter ''d'' as a suffix to indicate that it's a daemon. For example, is a daemon that implements system logging facility, and is a daemon that serves incoming SSH connections. Even though the concept can apply to many computing systems, the term ''daemon'' is used almost exclusively in the context of Unix-based systems. In other contexts, different terms are used for the same concept. Systems often start daemons at boot time that will respond to network requests, hardware activity, or other programs by performing some task. Daemons such as cron may also perform defined tasks at scheduled times. Terminology In the context of computing, the word is generally pronounced either as or . The term was coined by the programmers at MIT's Project MAC. According to Fernando J. Cor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Server (computing)
A server is a computer that provides information to other computers called " clients" on a computer network. This architecture is called the client–server model. Servers can provide various functionalities, often called "services", such as sharing data or resources among multiple clients or performing computations for a client. A single server can serve multiple clients, and a single client can use multiple servers. A client process may run on the same device or may connect over a network to a server on a different device. Typical servers are database servers, file servers, mail servers, print servers, web servers, game servers, and application servers. Client–server systems are usually most frequently implemented by (and often identified with) the request–response model: a client sends a request to the server, which performs some action and sends a response back to the client, typically with a result or acknowledgment. Designating a computer as "server-class hardwa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Debugging
In engineering, debugging is the process of finding the Root cause analysis, root cause, workarounds, and possible fixes for bug (engineering), bugs. For software, debugging tactics can involve interactive debugging, control flow analysis, Logfile, log file analysis, monitoring at the application monitoring, application or system monitoring, system level, memory dumps, and profiling (computer programming), profiling. Many Programming language, programming languages and Programming tool, software development tools also offer programs to aid in debugging, known as debuggers. Etymology The term ''bug'', in the sense of defect, dates back at least to 1878 when Thomas Edison wrote "little faults and difficulties" in his inventions as "Bugs". A popular story from the 1940s is from Admiral Grace Hopper. While she was working on a Harvard Mark II, Mark II computer at Harvard University, her associates discovered a moth stuck in a relay that impeded operation and wrote in a log book ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linux Standard Base
The Linux Standard Base (LSB) was a joint project by several Linux distributions under the organizational structure of the Linux Foundation to standardize the software system structure, including the Filesystem Hierarchy Standard. LSB was based on the POSIX specification, the Single UNIX Specification (SUS), and several other open standards, but extended them in certain areas. According to LSB: The goal of the LSB is to develop and promote a set of open standards that will increase compatibility among Linux distributions and enable software applications to run on any compliant system even in binary form. In addition, the LSB will help coordinate efforts to recruit software vendors to port and write products for Linux Operating Systems. LSB compliance might be certified for a product by a certification procedure. LSB specified standard libraries (centered around the ), a number of commands and utilities that extend the POSIX standard, the layout of the file system hierarchy, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
User Identifier
Unix-like operating systems identify a user by a value called a user identifier, often abbreviated to user ID or UID. The UID, along with the group identifier (GID) and other access control criteria, is used to determine which system resources a user can access. The Passwd (file), password file maps textual user names to UIDs. UIDs are stored in the inodes of the Unix file system, running processes, tar archives, and the now-obsolete Network Information Service. In POSIX-compliant environments, the shell command id gives the current user's UID, as well as more information such as the user name, primary user group and group identifier (GID). Process attributes The POSIX standard introduced three different UID fields into the process descriptor table, to allow privileged processes to take on different roles dynamically: Effective user ID The effective UID (euid) of a process is used for most access checks. It is also used as the owner for files created by that process. The effectiv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
