The EasyPost CLI is made up of shell scripts and curl requests. The design is unique and as such warrants a set of development documentation separate from the user documentation.
The EasyPost CLI is built in pure Bash and only requires cURL to work. There are certainly better ways to build a CLI like using a scripting or compile language and then distributing a single binary but I wanted to try doing things the hard way and build an entire project in Bash. There are a couple of instances of commands such as sed, cat, if statements, and others but the majority of everything happens via API calls over cURL. Although there are more powerful languages out there to build a command line tool with, the decision was made to use Shell and cURL for portability and simplicity. The EasyPost CLI should work across macOS, Linux, and Windows (when converted during the build process). On Unix system, the executable has been tested and can be built with bash, dash, sh, and ksh shells. Because the tool was built as Shell scripts, some creativity was necessary in creating a working executable with the minimal amount of dependencies and overhead.
The EasyPost CLI ultimately has 4 parts:
init script imports the config file and handles any other core functionality of the tool including running checks to ensure the environment is setup correctly and routing the command passed to the right function. This is built at the beginning of the executable. The shell shebang also lives here for Unix. (A init file can be found for both Unix and Windows.)src/functions directory.unix_ep.sh, and windows_ep.bat) are built from items 1 and 3. A build script concatenates all of these records into a single executable file which is then placed in the user’s path, ready to be called upon in the syntax of ep my_command.Note: Building should be done with each push to master!
When running the build script, you must pass a version number as the first parameter. Optionally, you can pass in bash, dash, sh, or ksh as a second parameter which will change the shebang on the compiled executable (Unix only). Bash is the default option; if a shell parameter is omitted, bash will be used.
./utils/build.sh 1.1.2 bash
There is an expiremental build functionality to convert the Bash EasyPost CLI into a Windows Batch equivelant. This logic lives in the windows-interpreter.sh file. The file is completely documented. The rationale is instead of developing the CLI for 2-3 sets of OS’s, we build the CLI in pure Bash and have a tool like this to convert it into a Windows equivelant. Building for windows happens at the same time as building for macOS/Linux.
The EasyPost CLI was intended to be used in bash but can instead be installed and run in sh, dash, or ksh if elected. Simply specify a different shell when building the executable or linting the project.
shellcheck src/*.sh --shell=dash
The EasyPost CLI website is currently hosted on GitHub Pages from the main branch and the docs folder. Each time a commit is made to master, the website will be built with any new changes to the docs folder.