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The test command in Unix evaluates the expression parameter. In most recent shell implementations, it is a shell builtin, even though the external version still exists.In the second form of the command, the [ ] (brackets) must be surrounded by blank spaces (this is because [is a program and POSIX compatible shells require a space between the program name and its arguments).
Predicates, which specify conditions that can be evaluated to SQL three-valued logic (3VL) (true/false/unknown) or Boolean truth values and are used to limit the effects of statements and queries, or to change program flow. Queries, which retrieve the data based on specific criteria. This is an important element of SQL.
MySQL (/ ˌ m aɪ ˌ ɛ s ˌ k juː ˈ ɛ l /) [5] is an open-source relational database management system (RDBMS). [5] [6] Its name is a combination of "My", the name of co-founder Michael Widenius's daughter My, [7] and "SQL", the acronym for Structured Query Language.
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From the early 1970s the Unix operating system adapted the concept of a powerful command-line environment, and introduced the ability to pipe the output of one command in as input to another. Unix also had the capability to save and re-run strings of commands as shell scripts which acted like custom commands.
yes can be used to send an affirmative (or negative; e.g. yes n) response to any command that would otherwise request one, thereby causing the command to run non-interactively. Piping yes to a command with many user-confirmation prompts will automatically answer all of those prompts with "yes" (typing 'y' and pressing return). The following ...
In Unix-like operating systems, find is a command-line utility that locates files based on some user-specified criteria and either prints the pathname of each matched object or, if another action is requested, performs that action on each matched object.
In either case, the shell redirects I/O appropriately, and sends the SIGCONT signal to the process, which causes the operating system to resume its execution. In Bash , a program can be started as a background job by appending an ampersand ( & ) to the command line; its output is directed to the terminal (potentially interleaved with other ...