Civil Rights
Movements, leaders, victories and the continuing fight for equality.
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Explore the people, places, events, achievements, struggles and stories that shaped our journey.
Movements, leaders, victories and the continuing fight for equality.
Innovation, patents, science, technology and world-changing contributions.
Pioneers, champions, Negro Leagues, records, activism and excellence.
Meet the people whose lives, choices and achievements shaped the journey.
Black towns, communities, institutions and places where history happened.
Moments that changed communities, movements, institutions and the nation.
Katherine Johnson’s mathematical calculations helped guide some of America’s most important early space missions while she confronted the racial and gender barriers faced by Black women in twentieth-century America.
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
| wait | |
|---|---|
| Developer | AT&T Bell Laboratories |
| Release | November 1973 |
| Operating system | Unix and Unix-like |
| Type | Command |
In Unix shells, wait is a command which pauses until execution of a background process has ended.
wait [n...]
where n... is a list of pids or job IDs of a currently executing background process (job). If no ids are provided, the command waits until all jobs known to the invoking shell have terminated.
wait normally returns the exit status of the last job which terminated. It may also return 127 in the event that n specifies a non-existent job or zero if there were no jobs to wait for.
Because wait needs to be aware of the job table of the current shell execution environment. Under the POSIX specifications it is required to be a shell builtin.[1]
This command can be useful where part of a script can execute in parallel to implement a barrier where an upcoming section depends on the successful completion of the preceding sections.
The following example will fetch the src/ directory from a machine named iona using rsync and simultaneously update the libraries on which this program depends, before building the combination.
#!/usr/bin/env bash
# Parallel update script which makes use of the wait command
# Update local copy
rsync iona:src/ . &
# Upgrade required libraries, or exit indicating failure if make failed for some reason
make -C lib || exit 1
# Wait for rsync to terminate (may have already happened) and finish the job
wait
make
Wait for specified job control id number:
$ ls -R / > /dev/null 2>&1 & # start any long running background process
[2] 1986
$ wait %2 # waits for background job number 2 to terminate, then returns
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|---|---|
| Processes | |
| User environment | |
| Text processing | |
| Shell builtins | |
| Searching | |
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Source: Wikipedia. Article content is retrieved live through the MediaWiki API.
In Unix shells, wait is a command which pauses until execution of a background process has ended.
A command-line interface (CLI), also known as a command-line shell, is a means of interacting with software via commands – each formatted as a line of text. The concept of interacting with a computer via text evolved over two decades, transitioning from physical hardware to sophisticated software. Before the CLI, computers were programmed using physical switches or punched cards. The shift toward a "command" style interaction began with the use of teleprinters/teletypes. Early systems like the Whirlwind I (1951) at MIT began utilizing typewriter-like inputs for direct control, moving away from batch processing where you'd hand a stack of cards to an operator and wait hours for a result. Devices like the Teletype Model 33, introduced in 1963, allowed operators to type a command and receive a printed response from the computer. The command-line interpreter emerged when computers became powerful enough to handle multiple users at once, known as time-sharing. The Compatible Time-Sharing System (CTSS), developed in 1961 at MIT, introduced the first true command-line interpreter. For the first time, a user could type a command like LOGIN or PRINT, and a dedicated program (the supervisor) would parse that text and execute the corresponding function. In 1964, Louis Pouzin introduced the software we now recognize as a "shell" for the Multics operating system, providing a programmable environment for executing scripts. Many utilities for operating system management and software development provide CLIs. Many CLIs enable software automation, since commands can be stored in a script file that can be used repeatedly. A script allows its contained commands to be executed as a group (as a single program). Alternatives to a CLI include a GUI (including the desktop metaphor such as Windows), text-based menuing (including DOS Shell and IBM AIX SMIT), and keyboard shortcuts.
On 26 September 1983, during the Cold War, the Soviet nuclear early warning system Oko reported the launch of one intercontinental ballistic missile with four more missiles behind it, from the United States. These missile attack warnings were suspected to be false alarms by Stanislav Petrov (1939–2017), an engineer of the Soviet Air Defence Forces on duty at the command center of the early-warning system. He decided to wait for corroborating evidence—of which none arrived—rather than immediately relaying the warning up the chain of command. This decision is seen as having prevented a retaliatory nuclear strike against the United States and its NATO allies, which would likely have resulted in a full-scale nuclear war. Investigation of the satellite warning system later determined that the system had indeed malfunctioned.
In computing, TIME is a command in DEC RT-11, DOS, IBM OS/2, Microsoft Windows and a number of other operating systems that is used to display and set the current system time. It is included in command-line interpreters (shells) such as COMMAND.COM, cmd.exe, 4DOS, 4OS2 and 4NT.
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 →The Greenwood District.
