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Nohup
nohup is a POSIX command which means "no hang up". Its purpose is to execute a command such that it ignores the HUP (hangup) signal and therefore does not stop when the user logs out. Output that would normally go to the terminal goes to a file called , if it has not already been redirected. Use The first of the commands below starts the program abcd in the background in such a way that the subsequent logout does not stop it. $ nohup abcd & $ exit Note that these methods prevent the process from being sent a 'stop' signal on logout, but if input/output is being received for these standard I/O files (stdin, stdout, or stderr), they will still hang the terminal. See Overcoming hanging, below. nohup is often used in combination with the nice command to run processes on a lower priority. $ nohup nice abcd & Implementations Some shells (e.g. bash) provide a shell builtin that may be used to prevent SIGHUP being sent or propagated to existing jobs, even if they were not sta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SIGHUP
On POSIX-compliant platforms, SIGHUP ("signal hang up") is a signal sent to a process when its controlling terminal is closed. It was originally designed to notify the process of a serial line drop. SIGHUP is a symbolic constant defined in the header file signal.h. History Access to computer systems for many years consisted of connecting a terminal to a mainframe system via a serial line and the RS-232 protocol. When a system of software interrupts, called signals, was being developed, one of those signals was designated for use on hangup. SIGHUP would be sent to programs when the serial line was dropped, often because the connected user terminated the connection by hanging up the modem. The system would detect the line was dropped via the lost Data Carrier Detect (DCD) signal. Signals have always been a convenient method of inter-process communication (IPC), but in early implementations there were no user-definable signals (such as the later additions of SIGUSR1 and SIGU ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Disown (Unix)
In the Unix shells ksh, bash, fish and zsh, the disown builtin command is used to remove jobs from the job table, or to mark jobs so that a SIGHUP signal is not sent to them if the parent shell receives it (e.g. if the user logs out). See also * nohup, a POSIX The Portable Operating System Interface (POSIX; ) is a family of standards specified by the IEEE Computer Society for maintaining compatibility between operating systems. POSIX defines application programming interfaces (APIs), along with comm ... command to ignore the HUP (hangup) signal External links Bash Reference Manual: Job Control Builtins {{Unix commands System administration ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Open-source Software
Open-source software (OSS) is Software, computer software that is released under a Open-source license, license in which the copyright holder grants users the rights to use, study, change, and Software distribution, distribute the software and its source code to anyone and for any purpose. Open-source software may be developed in a collaborative, public manner. Open-source software is a prominent example of open collaboration, meaning any capable user is able to online collaboration, participate online in development, making the number of possible contributors indefinite. The ability to examine the code facilitates public trust in the software. Open-source software development can bring in diverse perspectives beyond those of a single company. A 2024 estimate of the value of open-source software to firms is $8.8 trillion, as firms would need to spend 3.5 times the amount they currently do without the use of open source software. Open-source code can be used for studying and a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GNU Screen
GNU Screen is a terminal multiplexer: a software application that can be used to multiplex several virtual consoles, allowing a user to access multiple separate login sessions inside a single terminal window, or detach and reattach sessions from a terminal. It is useful for dealing with multiple programs from a command line interface, and for separating programs from the session of the Unix shell that started the program, particularly so a remote process continues running even when the user is disconnected. Released under the terms of version 3 or later of the GNU General Public License, GNU Screen is free software. Features GNU Screen can be thought of as a text version of graphical window managers, or as a way of putting virtual terminals into any login session. It is a wrapper that allows multiple text programs to run at the same time, and provides features that allow the user to use the programs within a single interface productively. This enables the following features: ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Terminal Multiplexer
A terminal multiplexer is a software application that can be used to multiplex several separate pseudoterminal-based login sessions inside a single terminal display, terminal emulator window, PC/workstation system console, or remote login session, or to detach and reattach sessions from a terminal. It is useful for dealing with multiple programs from a command line interface, and for separating programs from the session of the Unix shell that started the program, particularly so a remote process continues running even when the user is disconnected. Features A terminal multiplexer can be thought of as a text version of graphical window managers, or as a way of putting attach virtual terminals to any login session. It is a wrapper that allows multiple text programs to run at the same time, and provides features that allow the user to use the programs within a single interface productively. ; Persistence: Similar to Virtual Network Computing, many terminal multiplexers allow the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pseudo Terminal
In some operating systems, including Unix-like systems, a pseudoterminal, pseudotty, or PTY is a pair of pseudo-device endpoints (files) which establish an asynchronous, Duplex (telecommunications), bidirectional communication (IPC socket, IPC) channel (with two ports) between two or more processes. One pseudo-device in the pair, the ''master'', provides means by which a terminal emulator or remote login server (e.g. a Telnet, Berkeley r-commands, rlogin, or Secure Shell server) computer process, process controls the slave. The other pseudo-device, the ''slave'', emulates a hardware serial port device, and is used by terminal-oriented programs such as shells (e.g. Bash (Unix shell), bash) as a processes to read/write data back from/to ''master'' endpoint. PTYs are similar to bidirectional pipes. Devpts is a Linux kernel virtual file system containing pseudoterminal devices. Linux implementation is based on UNIX System V, System V-style terminals (commonly referred as UNIX 98 pse ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Redirection (computing)
In computing, redirection is a form of interprocess communication, and is a function common to most command-line interpreters, including the various Unix shells that can redirect standard streams to user-specified locations. The concept of redirection is quite old, dating back to the earliest operating systems (OS). A discussion of the design goals for redirection can be found already in the 1971 description of the input-output subsystem of the Multics OS. However, prior to the introduction of UNIX OS with its "pipes", redirection in operating systems was hard or even impossible to do. In Unix-like operating systems, programs do redirection with the system call, or its less-flexible but higher-level stdio analogues, and . Redirecting standard input and standard output Redirection is usually implemented by placing certain characters between commands. Basic Typically, the syntax of these characters is as follows, using < to redirect input, and > to redirect output. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Login Session
In computing, a login session is the period of activity between a user logging in and logging out of a (multi-user) system. On Unix and Unix-like operating systems, a login session takes one of two main forms: * When a textual user interface is used, a login session is represented as a kernel session — a collection of process groups with the logout action managed by a session leader. * Where an X display manager is employed, a login session is considered to be the lifetime of a designated user process that the display manager invokes. On Windows NT-based systems, login sessions are maintained by the kernel and control of them is overseen by the Local Security Authority Subsystem Service (LSA). winlogon responds to the secure attention key, it requests the LSA to create login sessions on login, and terminates all of the processes belonging to a login session on logout. See also * Booting process of Windows NT * Architecture of Windows NT * Booting * Master boot recor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Secure Shell
The Secure Shell Protocol (SSH Protocol) is a cryptographic network protocol for operating network services securely over an unsecured network. Its most notable applications are remote login and command-line execution. SSH was designed for Unix-like operating systems as a replacement for Telnet and unsecured remote Unix shell protocols, such as the Berkeley Remote Shell (rsh) and the related rlogin and rexec protocols, which all use insecure, plaintext methods of authentication, like passwords. Since mechanisms like Telnet and Remote Shell are designed to access and operate remote computers, sending the authentication tokens (e.g. username and password) for this access to these computers across a public network in an unsecured way poses a great risk of 3rd parties obtaining the password and achieving the same level of access to the remote system as the telnet user. Secure Shell mitigates this risk through the use of encryption mechanisms that are intended to hide th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solaris (operating System)
Oracle Solaris is a proprietary software, proprietary Unix operating system offered by Oracle Corporation, Oracle for SPARC and x86-64 based workstations and server (computing), servers. Originally developed by Sun Microsystems as Solaris, it superseded the company's earlier SunOS in 1993 and became known for its scalability, especially on SPARC systems, and for originating many innovative features such as DTrace, ZFS and Time Slider. After the Acquisition of Sun Microsystems by Oracle Corporation, Sun acquisition by Oracle in 2010, it was renamed Oracle Solaris. Solaris was registered as compliant with the Single UNIX Specification until April 29, 2019. Historically, Solaris was developed as proprietary software. In June 2005, Sun Microsystems released most of the codebase under the CDDL license, and founded the OpenSolaris Open-source software, open-source project. Sun aimed to build a developer and user community with OpenSolaris; after the Oracle acquisition in 2010, the Open ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IBM AIX
AIX (pronounced ) is a series of Proprietary software, proprietary Unix operating systems developed and sold by IBM since 1986. The name stands for "Advanced Interactive eXecutive". Current versions are designed to work with Power ISA based Server (computing), server and workstation computers such as IBM's IBM Power Systems, Power line. Background Originally released for the IBM RT PC Reduced instruction set computer, RISC workstation in 1986, AIX has supported a wide range of hardware platforms, including the IBM IBM RS/6000, RS/6000 series and later IBM Power microprocessors, Power and PowerPC-based systems, IBM System i, System/370 mainframes, IBM PS/2, PS/2 personal computers, and the Apple Network Server. Currently, it is supported on IBM Power Systems alongside IBM i and Linux. AIX is based on UNIX System V with 4.3BSD-compatible extensions. It is certified to the UNIX 03 and UNIX V7 specifications of the Single UNIX Specification, beginning with AIX versions 5.3 an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
