Job control – Operating Systems

Job control

Job control refers to the control of multiple tasks or jobs on a computer system, ensuring that they each have access to adequate resources to perform correctly, that competition for limited resources does not cause a deadlock where two or more jobs are unable to complete, resolving such situations where they do occur, and terminating jobs that, for any reason, are not performing as expected.

Job control language (JCL)

Short for Job Control Language, JCL is a scripting language that is used to communicate with the operating system. Using JCL, a user can submit a statement to the operating system, which it then uses to execute a job. JCL also enables the user to view resources needed to run a job and minor control details. A language used to construct statements that identify a particular job to be run and specify the job’s requirements to the operating system under which it will run.

A programming language used to specify the manner, timing, and other requirements of execution of a task or set of tasks submitted for execution, especially in background, on a multitasking computer; a programming language for controlling job execution.

Command language

Sometimes referred to as a command script, a command language is a language used for executing a series of commands instructions that would otherwise be executed at the prompt(text or symbols used to represent the system’s readiness to perform the next). A good example of a command language is Microsoft Windows batch files(A batch file or batch job is a collection, or list, of commands that are processed in sequence often without requiring user input or intervention).

Although command languages are useful for executing a series of commands, their functionality is limited to what is available at the command line which can make them easier to learn.

Advantages of command languages

  • Very easy for all types of users to write.
  • Do not require the files to be compiled.
  • Easy to modify and make additional commands.
  • Very small files.
  • Do not require any additional programs or files that are not already found on the operating system.

Disadvantages of command languages

  • Can be limited when comparing with other programming languages or scripting languages.
  • May not execute as fast as other languages or compiled programs.
  • Some command languages often offer little more than using the commands available for the operating system used.

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