Shell internal commands and external commands

Source: Internet
Author: User

Shell internal commands and external commands

Internal command: is actually part of the shell program, which is a command executed by the shell itself, usually loaded and resides inside the system when the Linux system loads and runs.

External command: Is the utility part of the system, because the utility is usually more powerful, so the amount of programs involved will be very large, when the system is not loaded with the system is loaded into memory, but need to call memory. the entity of the external command is not included in the shell, but its command execution process is controlled by the shell, the shell program manages the path lookup, loading and storage of the external command execution, and controls the execution of the command. You can use the Echo $PATH command to view the storage path for external commands.

The type distinguishes between internal commands and external commands.

When executing a command, the shell command interpreter should execute the internal instruction first, and the instruction to execute is not an internal instruction, it should be the external instruction of the call.

View Shell internal commands: [...] #man Builtins

Determine if a command is an internal command: [...] #type-a command

[...] #command--help View Help files for external commands

[...] #help command to view Help files for internal commands



Shell internal commands and external commands

Related Article

Contact Us

The content source of this page is from Internet, which doesn't represent Alibaba Cloud's opinion; products and services mentioned on that page don't have any relationship with Alibaba Cloud. If the content of the page makes you feel confusing, please write us an email, we will handle the problem within 5 days after receiving your email.

If you find any instances of plagiarism from the community, please send an email to: info-contact@alibabacloud.com and provide relevant evidence. A staff member will contact you within 5 working days.

A Free Trial That Lets You Build Big!

Start building with 50+ products and up to 12 months usage for Elastic Compute Service

  • Sales Support

    1 on 1 presale consultation

  • After-Sales Support

    24/7 Technical Support 6 Free Tickets per Quarter Faster Response

  • Alibaba Cloud offers highly flexible support services tailored to meet your exact needs.