shell

fisherman/pkg/shell

A package providing a lightweight cross-platform wrapper over the system shell.

Features:

• Expandable (implements shell.ShellStrategy interface to integrate)
• Shell host implements io.Writer interface to simple put commands into stdin.
• The commands are executed after entering a new line. This can be used to execute commands over time using a single terminal process.

Available shell strategies

• shell.Cmd() - Strategy to use cmd.exe as shell host. Can be used only on windows. It is also the default shell for windows.
• shell.Bash() - Strategy to use bash as shell host. Available on windows, linux and darwin. It is the default shell for linux and darwin. Note: for windows bash available only in package MSYS2.
• shell.PowerShell() - Strategy to use powershell as shell host. Can be used on windows, linux and darwin.

Options

• shell.WithCwd(dir) - specifies the working directory of the shell. If it is the empty ot not set, host runs the shell in the calling process's current directory.
• shell.WithStdout(output) - specify the process's standard output.
• shell.WithStderr(output) - specify the process's standard error.
• shell.WithEnv(env) - specifies the environment of the shell process (including the shell strategy provided variables).
• shell.WithRawEnv(env) - specifies the environment of the shell process (without the shell strategy provided variables).
• shell.WithArgs(args) - holds command line arguments (including the shell strategy provided args)
• shell.WithRawArgs(args) - holds command line arguments (without the shell strategy provided args)
• shell.WithEncoding(encoding) - overwrite encoding for shell. (To setup utf-8 encoding pass encoding.Nop)

Examples

Basic

ctx := context.Background()
host := shell.NewHost(ctx, shell.Cmd())

if err := host.Run("echo 'this is demo shell' >> log.txt"); err != nil {
  panic(err)
}

Advanced script input

ctx := context.Background()
host := shell.NewHost(ctx, shell.Cmd())

_, err = fmt.Fprintln(host, "echo 'this is demo shell' >> log.txt")
if err != nil {
  panic(err)
}


_, err = fmt.Fprintln(host, "ping -n 10 google.com")
if err != nil {
  panic(err)
}

if err := host.Wait(); err != nil {
  panic(err)
}

Collect shell output

buffer := bytes.NewBufferString("")

ctx := context.Background()
host := shell.NewHost(ctx, shell.Cmd(), shell.WithStdout(buffer))
if err := host.Run("ping -n 10 google.com"); err != nil {
  panic(err)
}

fmt.Print(buffer.String())

Custom encoding

buffer := bytes.NewBuffer([]byte{})

host := shell.NewHost(
  ctx,
  shell.Cmd(),
  shell.WithStdout(buffer),
  shell.WithEncoding(charmap.Windows1251),
)

fmt.Fprintln(host, "chcp 1251 > nul")
fmt.Fprintln(host, "echo проверка русского текста")

if err := host.Wait(); err != nil {
  panic(err)
}

fmt.Print(buffer.String())

Helpers

Also, the package contains helpers functions in fisherman/pkg/shell/helpers. These functions can be useful when working with shell host.

MergeEnv

• helpers.MergeEnv - Merges a slice of environment variables (for example os.Environ()) with a map of custom variables. In case when variable already defined in slice, it will replaced from map.

Known issues

There is a problem with rendering utf8 output on windows. This is related to the problem with UTF-8 support in Windows. ReadConsoleA and ReadFile just silently fail with the code page set to 65001. Read more here.