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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 ...
In Linux, if the script was executed by a regular user, the shell would attempt to execute the command rm -rf / as a regular user, and the command would fail. However, if the script was executed by the root user, then the command would likely succeed and the filesystem would be erased. It is recommended to use sudo on a per-command basis instead.
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.
A shell script can be used to provide a sequencing and decision-making linkage around existing programs, and for moderately sized scripts the absence of a compilation step is an advantage. Interpretive running makes it easy to write debugging code into a script and re-run it to detect and fix bugs.
The dangling else is a problem in programming of parser generators in which an optional else clause in an if–then(–else) statement can make nested conditional statements ambiguous. Formally, the reference context-free grammar of the language is ambiguous , meaning there is more than one correct parse tree .
One of the problems with the script command is that it only allows logging of a child process; and often there is a need to log the command in the current process without spawning a new process, such as when automation of a script is needed that can log its own output. The Unix operating systems make this possible by use of pipes and redirects ...
Bourne-Again shell (bash): written as part of the GNU Project to provide a superset of Bourne Shell functionality. This shell can be found installed and is the default interactive shell for users on most Linux systems. KornShell (ksh): written by David Korn based on the Bourne shell sources [8] while working at Bell Labs; Public domain Korn ...
Example of command-line completion in Bash. Example of command-line completion in PowerShell with Intellisense.. Command-line completion (also tab completion) is a common feature of command-line interpreters, in which the program automatically fills in partially typed commands.