get.sh is a tool for retrieving environment information for scripting with go modules

get.sh

#!/usr/bin/env bash
this=$0
prog=$(basename $0)
current=$prog
quickusage="Run '$prog help' for usage."

quickusage() {
    echo ""
    echo "$current: unknown command"
    echo "$quickusage"
    exit 126
}

expect() {
    local inlineusage=$1
    shift
    if [[ -z "$1" ]]; then
        echo "Usage: $current $inlineusage"
        echo "$quickusage"
        exit 126
    fi
    current="$current $1"
}

cmd_help() {
  usage="$prog is a tool for retrieving environment information for scripting with go modules.

Usage:

    $prog <command> [arguments]

The commands are:

    gopath                 print the current gopath or default to ~/go
    mod
        srcpath <import>   print the location of 'import' from GOPATH/pkg/mod
"
  echo "$usage"
}

cmd_gopath() {
    if [[ -n "$GOPATH" ]]; then
        echo $GOPATH
    else
        echo ~/go
    fi
}

cmd_mod() {
    set -eo pipefail

    subcmd=$1 ; expect "srcpath [arguments]" $@ ; shift
    case $subcmd in
    srcpath)
        import=$1 ; expect "<import>" $@ ; shift
        srcpath=$(go list -m $import)
        echo $($this gopath)/pkg/mod/${srcpath/ /@}
        ;;
    *)
        quickusage
    esac
}

command=$1 ; expect "<command>" $@ ; shift
case $command in
"-h" | "--help")
    cmd_help
    ;;
*)
    cmd_${command} $@
    if [[ $? == 127 ]]; then quickusage ; fi
esac