loggedexec

Documentation

Overview

loggedexec is a wrapper around os/exec which logs command execution, the command’s stdout/stderr into files and provides better error messages when command execution fails. This makes debugging easier for end users.

Index

• type LoggedCmd
  • func Command(name string, arg ...string) *LoggedCmd
  • func (l *LoggedCmd) Run() error

Examples

• Command

Types

type LoggedCmd

type LoggedCmd struct {
	*exec.Cmd

	// Logger will be used to log invocation commands for human
	// consumption. Defaults to logging to os.Stderr. Use
	// ioutil.Discard to hide logs.
	Logger *log.Logger

	// LogDir is the directory in which log files will be
	// created. Defaults to os.TempDir().
	LogDir string

	// LogFmt is the prefix used for naming log files in
	// LogDir. Defaults to "%03d-" and must contain precisely one "%d"
	// which will be replaced with the invocation count.
	LogFmt string
}

LoggedCmd is like (os/exec).Cmd, but its Run() method additionally:

• Logs each invocation’s command for human consumption.
• Logs each invocation’s working directory, Args, Env and timing into a file.
• Logs each invocation’s stdout/stderr into a file.
• Wraps the returned error (if any) with the command and pointers to the log files with more details (including the first line of stdout/stderr).

All files are created in LogDir.

func Command

func Command(name string, arg ...string) *LoggedCmd

Command is like (os/exec).Command, but returns a LoggedCmd.

Example

package main

import (
	"fmt"

	"github.com/Debian/mergebot/loggedexec"
)

func main() {
	cmd := loggedexec.Command("ls", "/tmp/nonexistant")
	cmd.Env = []string{"LANG=C"}
	if err := cmd.Run(); err != nil {
		fmt.Println(err)
	}
}

Output:

Running "ls /tmp/nonexistant": exit status 2
See "/tmp/000-ls.invocation.log" for invocation details.
See "/tmp/000-ls.stdoutstderr.log" for full stdout/stderr.
First stdout/stderr line: "ls: cannot access /tmp/nonexistant: No such file or directory"

func (*LoggedCmd) Run

func (l *LoggedCmd) Run() error

Run is a wrapper around (os/exec).Cmd’s Run().