Here are steps to configure Terminal to run telnet at startup. You can then use that explicit path for your Terminal profile settings. You can use which telnet to see where it lives. If you're able to simply run telnet from inside Terminal, then that means that you've already installed it somewhere and it's able to be located via your PATH environment variable.

gnu netutils contains one such implementation.

When you do have a need for it, you can install it by using one of the standard macOS software port repositories, such as Homebrew, or by compiling and installing it yourself from source. Telnet is no longer included by default in macOS installs, as it is a rarely-used and extremely insecure protocol. Reset the Launch Services PATH to default with: sudo launchctl config user path '' We fix this by adding the telnet installation directory to the PATH with launchctl config user path, see launchctl(1). Those directories are all under System Integrity Protection so we could/should not have installed telnet to any of them. The current value of this PATH can be printed with launchctl getenv PATH if empty, the default is /usr/bin:/bin:/usr/sbin:/sbin as seen by sysctl -n user.cs_path.

It fails when the Launch Services PATH does not contain the telnet installation directory. However, even after the installation it still might fail: $ open telnet://localhost:23 ExplanationĪpplications can register their ablility to handle the telnet:// URL Scheme with Launch Services, like Terminal.app has done in /System/Applications/Utilities/Terminal.app/Contents/ist: CFBundleURLTypesīut telnet is no longer provided by macOS, so we have to install it ourselves, by brew install telnet or by following a guide of How to Get Telnet. This assumes that launchctl getenv PATH returns an empty string and that telnet is in the shells PATH. Install telnet and add its installation directory to the Launch Services PATH: sudo launchctl config user path '$(sysctl -n user.cs_path):$(dirname '$(command -v telnet)')'

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