diff options
Diffstat (limited to 'cmd.go')
| -rw-r--r-- | cmd.go | 184 |
1 files changed, 184 insertions, 0 deletions
@@ -0,0 +1,184 @@ +package main + +// this is a simplified interaction with the excellent +// go-cmd/cmd package to work 'shell' like. + +// in all cases here, STDERR -> STDOUT +// If you want the output from whatever you run +// to be captured like it appears when you see it +// on the command line, this is what this tries to do + +/* + if r := shell.Run([]{"ping", "-c", "3", "localhost"}); r.Error == nil { + if r.Exit == 0 { + log.Println("ran ok") + } else { + log.Println("ran") + } + // all stdout/stderr captured in r.Stdout + } +*/ + +import ( + "errors" + "fmt" + "time" + + "github.com/go-cmd/cmd" + "go.wit.com/log" +) + +func Run(args []string) cmd.Status { + return PwdRun("", args) +} + +// absolutely doesn't echo anything +func PwdRunQuiet(pwd string, args []string) cmd.Status { + var arg0 string + var argx []string + // Check if the slice has at least one element (the command name) + if len(args) == 0 { + var s cmd.Status + s.Error = errors.New("Error: Command slice is empty.") + return s + } + if len(args) == 1 { + // Pass the first element as the command, and the rest as variadic arguments + arg0 = args[0] + } else { + arg0 = args[0] + argx = args[1:] + } + + // Start a long-running process, capture stdout and stderr + findCmd := cmd.NewCmd(arg0, argx...) + if pwd != "" { + findCmd.Dir = pwd + } + statusChan := findCmd.Start() // non-blocking + + ticker := time.NewTicker(2 * time.Second) + + // this is interesting, maybe useful, but wierd, but neat. interesting even + // Print last line of stdout every 2s + go func() { + for range ticker.C { + status := findCmd.Status() + n := len(status.Stdout) + if n != 0 { + fmt.Println(status.Stdout[n-1]) + } + } + }() + + // Stop command after 1 hour + go func() { + <-time.After(1 * time.Hour) + findCmd.Stop() + }() + + // Check if command is done + select { + case finalStatus := <-statusChan: + log.Info("finalStatus =", finalStatus.Exit, finalStatus.Error) + return finalStatus + // done + default: + // no, still running + } + + // Block waiting for command to exit, be stopped, or be killed + finalStatus := <-statusChan + return finalStatus +} + +func blah(cmd []string) { + r := Run(cmd) + log.Info("cmd =", r.Cmd) + log.Info("complete =", r.Complete) + log.Info("exit =", r.Exit) + log.Info("err =", r.Error) + log.Info("len(stdout+stderr) =", len(r.Stdout)) +} + +// run these to see confirm the sytem behaves as expected +func RunTest() { + blah([]string{"ping", "-c", "3", "localhost"}) + blah([]string{"exit", "0"}) + blah([]string{"exit", "-1"}) + blah([]string{"true"}) + blah([]string{"false"}) + blah([]string{"grep", "root", "/etc/", "/proc/cmdline", "/usr/bin/chmod"}) + blah([]string{"grep", "root", "/proc/cmdline"}) + fmt.Sprint("blahdone") +} + +// sets the exec dir if it's sent +// combines stdout and stderr +// echo's output +func PwdRun(pwd string, args []string) cmd.Status { + var save []string // combined stdout & stderr + var arg0 string + var argx []string + // Check if the slice has at least one element (the command name) + if len(args) == 0 { + var s cmd.Status + s.Error = errors.New("Error: Command slice is empty.") + return s + } + if len(args) == 1 { + // Pass the first element as the command, and the rest as variadic arguments + arg0 = args[0] + } else { + arg0 = args[0] + argx = args[1:] + } + + // Disable output buffering, enable streaming + cmdOptions := cmd.Options{ + Buffered: false, + Streaming: true, + } + + // Create Cmd with options + envCmd := cmd.NewCmdOptions(cmdOptions, arg0, argx...) + if pwd != "" { + envCmd.Dir = pwd + } + + // Print STDOUT and STDERR lines streaming from Cmd + doneChan := make(chan struct{}) + go func() { + defer close(doneChan) + // Done when both channels have been closed + // https://dave.cheney.net/2013/04/30/curious-channels + for envCmd.Stdout != nil || envCmd.Stderr != nil { + select { + case line, open := <-envCmd.Stdout: + if !open { + envCmd.Stdout = nil + continue + } + save = append(save, line) + fmt.Println(line) + case line, open := <-envCmd.Stderr: + if !open { + envCmd.Stderr = nil + continue + } + save = append(save, line) + fmt.Println(line) + } + } + }() + + // Run and wait for Cmd to return, discard Status + <-envCmd.Start() + + // Wait for goroutine to print everything + <-doneChan + + s := envCmd.Status() + s.Stdout = save + return s +} |