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The detailed semantics of "the" ternary operator as well as its syntax differs significantly from language to language. A top level distinction from one language to another is whether the expressions permit side effects (as in most procedural languages) and whether the language provides short-circuit evaluation semantics, whereby only the selected expression is evaluated (most standard ...
If-then-else flow diagram A nested if–then–else flow diagram. In computer science, conditionals (that is, conditional statements, conditional expressions and conditional constructs) are programming language constructs that perform different computations or actions or return different values depending on the value of a Boolean expression, called a condition.
The true command is sometimes substituted with the very similar null command, [1] written as a single colon (:).The null command is built into the shell, and may therefore be more efficient if true is an external program (true is usually a shell built in function).
The Bourne shell (sh) is a shell command-line interpreter for computer operating systems.It first appeared on Version 7 Unix, as its default shell. Unix-like systems continue to have /bin/sh—which will be the Bourne shell, or a symbolic link or hard link to a compatible shell—even when other shells are used by most users.
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).
ALGOL 68 (short for Algorithmic Language 1968) is an imperative programming language that was conceived as a successor to the ALGOL 60 programming language, designed with the goal of a much wider scope of application and more rigorously defined syntax and semantics.
Editing a FreeBSD shell script for configuring ipfirewall. A shell script is a computer program designed to be run by a Unix shell, a command-line interpreter. [1] The various dialects of shell scripts are considered to be command languages. Typical operations performed by shell scripts include file manipulation, program execution, and printing ...
The C shell can also read commands from a file, called a script. Like all Unix shells, it supports filename wildcarding, piping, here documents, command substitution, variables and control structures for condition-testing and iteration. What differentiated the C shell from others, especially in the 1980s, were its interactive features and ...