README
¶
Package cloudeng.io/os/executil
import cloudeng.io/os/executil
Package executil provides utilities for working with os/exec.
Functions
Func ExecName
func ExecName(path string) string
ExecName returns path in a form suitable for use as an executable. For unix systems the path is unchanged. For windows a '.exe' suffix is added if not already present.
Func Getenv
func Getenv(env []string, key string) (string, bool)
Getenv retrieves the value of an environment variable from the provided slice.
Func GoBuild
func GoBuild(ctx context.Context, binary string, args ...string) (string, error)
Func IsStopped
func IsStopped(pid int) bool
IsStopped returns true if the process with the specified pid has stopped or does not exist. Wait must have been called on the process otherwise this function will return true on some systems since the process may still exist as a defunct process.
Func NewLineFilter
func NewLineFilter(forward io.Writer, ch chan<- []byte, res ...*regexp.Regexp) io.WriteCloser
NewLineFilter returns an io.WriteCloser that scans the contents of the supplied io.Writer and sends lines that match the regexp to the supplied channel. It can be used to filter the output of a command started by the exec package for example for specific output. If no regexps are supplied, all lines are sent. Close must be called on the returned io.WriteCloser to ensure that all resources are reclaimed.
Func ReplaceEnvVar
func ReplaceEnvVar(env []string, key, value string) []string
ReplaceEnvVar replaces the value of an environment variable in the provided slice. If the variable does not exist, it is added to the slice.
Func SignalAndWait
func SignalAndWait(ctx context.Context, perSignalOrWait time.Duration, cmd *exec.Cmd, sigs ...os.Signal) error
SignalAndWait provides a convenience function to signal a process to terminate by sending it one or more signals and waiting for it to terminate but with a timeout on calling Wait and on waiting for the process to stop after each signal. The perSignalOrWait duration is used as the timeout for both calling Wait and for waiting for the process to stop after each signal, hence the total time spent waiting may be up to len(sigs)+1 times perSignalOrWait. If the process stops after any signal, SignalAndWait returns immediately.
Func WaitForStopped
func WaitForStopped(ctx context.Context, pid int, waitFor time.Duration) error
WaitForStopped waits for the process with the specified pid to stop within the specified duration. It assumes that Wait has been called.
Examples
Example
TODO
- cnicolaou: make sure all goroutines shutdown.
Documentation
¶
Overview ¶
Package executil provides utilities for working with os/exec.
Example ¶
package main
import (
"bytes"
"context"
"fmt"
"os"
"os/exec"
"path/filepath"
"regexp"
"runtime"
"sync"
"time"
"cloudeng.io/os/executil"
)
func main() {
go func() {
time.Sleep(time.Second * 5)
buf := make([]byte, 1024*1024)
n := runtime.Stack(buf, true)
fmt.Fprintf(os.Stderr, "%s\n", string(buf[:n]))
os.Exit(1)
}()
ctx := context.Background()
all := &bytes.Buffer{}
// Use go run testdata/cat.go for compatibility across windows and unix.
cmd := exec.CommandContext(ctx, "go", "run", filepath.Join("testdata", "cat.go"), filepath.Join("testdata", "example")) // #nosec G204
ch := make(chan []byte, 1)
filter := executil.NewLineFilter(all, ch, regexp.MustCompile("filter me:"))
cmd.Stdout = filter
var wg sync.WaitGroup
wg.Add(1)
go func() {
if err := cmd.Start(); err != nil {
panic(err)
}
wg.Done()
}()
buf := <-ch
fmt.Println("filtered output")
fmt.Println(string(buf))
fmt.Println("all of the output")
wg.Wait()
if err := filter.Close(); err != nil {
fmt.Println(err)
}
fmt.Println(all.String())
}
Output: filtered output filter me: 33 all of the output some words some more words filter me: 33 and again more words
Index ¶
- func ExecName(path string) string
- func Getenv(env []string, key string) (string, bool)
- func GoBuild(ctx context.Context, binary string, args ...string) (string, error)
- func IsStopped(pid int) bool
- func NewLineFilter(forward io.Writer, ch chan<- []byte, res ...*regexp.Regexp) io.WriteCloser
- func ReplaceEnvVar(env []string, key, value string) []string
- func SignalAndWait(ctx context.Context, perSignalOrWait time.Duration, cmd *exec.Cmd, ...) error
- func WaitForStopped(ctx context.Context, pid int, waitFor time.Duration) error
Examples ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func ExecName ¶
ExecName returns path in a form suitable for use as an executable. For unix systems the path is unchanged. For windows a '.exe' suffix is added if not already present.
func IsStopped ¶
IsStopped returns true if the process with the specified pid has stopped or does not exist. Wait must have been called on the process otherwise this function will return true on some systems since the process may still exist as a defunct process.
func NewLineFilter ¶
NewLineFilter returns an io.WriteCloser that scans the contents of the supplied io.Writer and sends lines that match the regexp to the supplied channel. It can be used to filter the output of a command started by the exec package for example for specific output. If no regexps are supplied, all lines are sent. Close must be called on the returned io.WriteCloser to ensure that all resources are reclaimed.
func ReplaceEnvVar ¶
ReplaceEnvVar replaces the value of an environment variable in the provided slice. If the variable does not exist, it is added to the slice.
func SignalAndWait ¶
func SignalAndWait(ctx context.Context, perSignalOrWait time.Duration, cmd *exec.Cmd, sigs ...os.Signal) error
SignalAndWait provides a convenience function to signal a process to terminate by sending it one or more signals and waiting for it to terminate but with a timeout on calling Wait and on waiting for the process to stop after each signal. The perSignalOrWait duration is used as the timeout for both calling Wait and for waiting for the process to stop after each signal, hence the total time spent waiting may be up to len(sigs)+1 times perSignalOrWait. If the process stops after any signal, SignalAndWait returns immediately.
Types ¶
This section is empty.
Source Files