Golang filename without extension.go

package main

import (
	"strings"
	"path/filepath"
)

func fileNameWithoutExtension(fileName string) string {
	return strings.TrimSuffix(fileName, filepath.Ext(fileName))
}

ok fair enough, filepath.Ext() agrees:

The extension is the suffix beginning at the final dot in the final element of path

Bash has a few different ways of getting the extension, depending on what you want:

~% FILE="example.tar.gz"

~% echo "${FILE%%.*}"
example

~% echo "${FILE%.*}"
example.tar

~% echo "${FILE#*.}"
tar.gz

~% echo "${FILE##*.}"
gz

It may be a good safeguard to have filename go through filepath.Base() first

return strings.TrimSuffix(filepath.Base(fileName), filepath.Ext(fileName))

If the extension is static (always having a certain value), then a simple strings.CutSuffix(_,_) does the job. Example:

filenameWithoutExt, _ := strings.CutSuffix(filename, ".go")