CLI (Command Line Interface) programs are applications that are interacted with via a text interface, as opposed to a GUI (Graphical User Interface). In CLI programs, users type commands in text form and receive text responses, making them more suited to scripting and automation.

Here are a few types of CLI programs along with examples:

Shell Programs:

  • E.g., Bash, Zsh, and PowerShell.
  • These programs provide command-line interfaces for system interaction, allowing users to navigate the filesystem, manage processes, and execute other programs.

System Utilities:

  • E.g., grep, sed, awk, find.
  • These utilities provide specific functionalities for text processing, file searching, and system management.

Compilers and Interpreters:

  • E.g., GCC (GNU Compiler Collection), Python, Perl, Ruby.
  • These programs translate code written in a particular programming language into executable code, or interpret and execute the code directly.

Networking Tools:

  • E.g., ssh, scp, curl, wget.
  • These tools provide functionalities for networking, like remote access to machines, file transfers, and HTTP requests.

Version Control Systems:

  • E.g., git, svn (Subversion).
  • These tools help manage different versions of code and collaborate with other developers.

Package Managers:

  • E.g., apt (on Debian-based systems), yum (on Red Hat-based systems), npm (Node Package Manager), pip (Python Package Index).
  • These tools help manage software packages, allowing users to install, update, and remove software.

Database Clients:

  • E.g., mysql, psql (for PostgreSQL).
  • These CLI programs allow interaction with databases, enabling users to run queries, manage databases, and perform administrative tasks.

Custom CLI Programs:

  • Developers often create custom CLI programs to provide a text-based interface to their software. This can be done in various programming languages like Python (with libraries such as argparse or click), Ruby, Go, or even C.

CLI programs are often favored by power users, system administrators, and developers for their speed, precision, and scriptability. They may lack the intuitive interfaces of GUI programs, but they make up for it in flexibility and efficiency, especially in professional or server environments.