Gexpect
Gexpect is a pure golang expect-like module.
It makes it simpler to create and control other terminal applications.
child, err := gexpect.Spawn("python")
if err != nil {
panic(err)
}
child.Expect(">>>")
child.SendLine("print 'Hello World'")
child.Interact()
child.Close()
Examples
Spawn handles the argument parsing from a string
child.Spawn("/bin/sh -c 'echo \"my complicated command\" | tee log | cat > log2'")
child.ReadLine() // ReadLine() (string, error)
child.ReadUntil(' ') // ReadUntil(delim byte) ([]byte, error)
ReadLine, ReadUntil and SendLine send strings from/to stdout/stdin respectively
child, _ := gexpect.Spawn("cat")
child.SendLine("echoing process_stdin") // SendLine(command string) (error)
msg, _ := child.ReadLine() // msg = echoing process_stdin
Wait and Close allow for graceful and ungraceful termination.
child.Wait() // Waits until the child terminates naturally.
child.Close() // Sends a kill command
AsyncInteractChannels spawns two go routines to pipe into and from stdout/stdin, allowing for some usecases to be a little simpler.
child, _ := gexpect.Spawn("sh")
sender, receiver := child.AsyncInteractChannels()
sender <- "echo Hello World\n" // Send to stdin
line, open := <- receiver // Recieve a line from stdout/stderr
// When the subprocess stops (e.g. with child.Close()) , receiver is closed
if open {
fmt.Printf("Received %s", line)
}
ExpectRegex uses golang's internal regex engine to wait until a match from the process with the given regular expression (or an error on process termination with no match).
child, _ := gexpect.Spawn("echo accb")
match, _ := child.ExpectRegex("a..b")
// (match=true)
ExpectRegexFind allows for groups to be extracted from process stdout. The first element is an array of containing the total matched text, followed by each subexpression group match.
child, _ := gexpect.Spawn("echo 123 456 789")
result, _ := child.ExpectRegexFind("\d+ (\d+) (\d+)")
// result = []string{"123 456 789", "456", "789"}
See gexpect_test.go and the examples folder for full syntax
Credits
github.com/kballard/go-shellquote
github.com/kr/pty
KMP Algorithm: "http://blog.databigbang.com/searching-for-substrings-in-streams-a-slight-modification-of-the-knuth-morris-pratt-algorithm-in-haxe/"