execmd

execmd

ExecCmd is a Go package that offers a simplified interface for shell command execution. Built on top of the exec, ExecCmd enables command invocation in a system shell and combines multiple stdout and stderr into a single stdout with prefixes. It supports both local and remote command execution, with remote commands implemented through the OpenSSH binary.

Key features

• Execute commands in the system shell
• Execute remote shell commands using OpenSSH binary
• Capture outputs for programmatic access
• Real-time stdout and stderr output featuring auto coloring and prefixing
• Utilize shell variables, pipes, and redirections
• Compatibility with system SSH configuration (including ssh-agent forwarding)
• Run commands on multiple remote hosts (ideal for cluster operations) with parallel or serial execution options
• Minimum number of third party dependencies

Installation

go get "github.com/mikhae1/execmd"

Then import exec-cmd in your application:

import "github.com/mikhae1/execmd"

Examples

Local command execution

package main

import "github.com/mikhae1/execmd"

func main() {
  // run local command in a shell
  execmd.NewCmd().Run("ps aux | grep go")
}

Remote command execution

package main

import "github.com/mikhae1/execmd"

func main() {
  // run command on a remote host using ssh
  remote := execmd.NewSSHCmd("192.168.1.194")
  res, err := remote.Run(`VAR="$(hostname)"; echo "hello $VAR"`)

  if err == nil {
    fmt.Printf("captured output: %s", res.Stdout)
  }
}

Results:

$ /usr/bin/ssh 192.168.1.194 'VAR="$(hostname)"; echo "hello $VAR"'
192.168.1.194 hello host-01.local
captured output: hello host-01.local

Remote cluster command execution

cluster := execmd.NewClusterSSHCmd([]string{"host-01", "host-02", "host-03"})

// execute in parallel order
res, err := cluster.Run(`VAR=std; echo "Hello $VAR out"; echo Hello $VAR err >&2`)

// execute in serial order
res, err = cluster.RunOneByOne(`VAR=std; echo "Hello $VAR out"`)

Parallel execution results:

$ /usr/bin/ssh host-01 'VAR=std; echo "Hello $VAR out"; echo "Hello $VAR err" >&2'
$ /usr/bin/ssh host-02 'VAR=std; echo "Hello $VAR out"; echo "Hello $VAR err" >&2'
$ /usr/bin/ssh host-03 'VAR=std; echo "Hello $VAR out"; echo "Hello $VAR err" >&2'
host-01 Hello std out
host-01@err Hello std err
host-03@err Hello std err
host-03 Hello std out
host-02 Hello std out
host-02@err Hello std err

Serial execution results:

$ /usr/bin/ssh host-01 'VAR=std; echo "Hello $VAR out"; echo Hello $VAR err >&2'
host-01 Hello std out
host-01@err Hello std err
$ /usr/bin/ssh host-02 'VAR=std; echo "Hello $VAR out"; echo Hello $VAR err >&2'
host-02@err Hello std err
host-02 Hello std out
$ /usr/bin/ssh host-03 'VAR=std; echo "Hello $VAR out"; echo Hello $VAR err >&2'
host-03@err Hello std err
host-03 Hello std out

Testing

You should enable SSH server locally and add your personal ssh key to known_hosts to avoid password prompting:

ssh-copy-id 127.0.0.1
ssh-copy-id localhost

Run tests:

go test

License

The MIT License (MIT) - see LICENSE for details.