Handle shell built-in commands

[Itai-Nelken]

This handles built-in shell commands. this is done by using 2 arrays:

1. unhandled_shell_builtins: A string array containing the names of built-in commands that don't work through DollarSkip (cd for example).
2. handled_shell_builtins: An array for Wrapper (struct wrapper) that holds commands we wrapped so they work through DollarSkip.

To show how the handled shell built-ins work I added an "easter egg" command (e_egg). I thought about doing pwd, but I don't want to rewrite the bash version.

Closes #46

Signed-off-by: Itai-Nelken [email protected]

[Itai-Nelken]

Something I forgot to mention: this slows down dollarskip by about 0.030 seconds.

[CleanMachine1]

Something I forgot to mention: this slows down dollarskip by about 0.030 seconds.

Thats an extremely long time. I'm sure the average person will notice :smile:

There is no issue.

[Itai-Nelken]

I made a version of the changes here (excluding the "wrapping" of commands) for DollarSkip-go. the true in all entries of the map don't do anything and are there because I wanted to use a map as it makes it possible to not use loops, and so is faster.

package main

import (
	"fmt" // for printing errors
	"os"      // for capturing argv
	"os/exec" // for running the commands
	"strings" // for unslicing the array
)

var unhandled_commands = map[string]bool{
	"cd": true,
	"alias" : true,
	"unalias" : true,
	"pushd" : true,
	"popd" : true,
	"dirs" : true,
	"read" : true,
	"set" : true,
	"readonly" : true,
	"unset" : true,
	"typeset" : true,
	"declare" : true,
	"disown" : true,
	"enable" : true,
	"export" : true,
	"exit" : true, // doesn't do anything when run through DollarSkip
	"fc" : true,
	"history" : true,
	"fg" : true,
	"getopts" : true,
	"hash" : true, // we don't want it to report fake data for the current shell (true for the shell in which it is run)
	"jobs" : true, // same reason as the one for 'hash'
	"times" : true, // same as above
	"local" : true,
}

func main() {
	if len(os.Args) < 2 {
		os.Exit(1)
	}
	if _, ok := unhandled_commands[os.Args[1]]; ok {
		fmt.Fprintf(os.Stderr, "\x1b[31;1m[DollarSkip: error]: '\x1b[97m%s\x1b[0;1;31m': built-in shell commands aren't supported!\x1b[0m\n", os.Args[1])
		os.Exit(1)
	}
	args := os.Args[1:]                               // collects given arguments and 1: removes the binary name
	unsliced_string := strings.Join(args, " ")        // convert to string rather than type []string from args
	shell := os.Getenv("SHELL")                       // Using the env, save the shell
	cmd := exec.Command(shell, `-c`, unsliced_string) // Define the command to be run
	cmd.Stderr = os.Stderr
	cmd.Stdout = os.Stdout
	cmd.Stdin = os.Stdin

	err := cmd.Run() // Run the command
	if exitErr, ok := err.(*exec.ExitError); ok {
		exitCode := exitErr.ExitCode()
		os.Exit(exitCode)

	} else if err != nil {
		exitCode := 1
		os.Exit(exitCode)

	}

}