The following works and prints the command output:
out, err := exec.Command("ps", "cax").Output()
but this one fails (with exit status 1):
out, err := exec.Command("ps", "cax | grep myapp").Output()
Any suggestions?
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3 Answers
Passing everything to bash works, but here's a more idiomatic way of doing it.
package main
import (
"fmt"
"os/exec"
)
func main() {
grep := exec.Command("grep", "redis")
ps := exec.Command("ps", "cax")
// Get ps's stdout and attach it to grep's stdin.
pipe, _ := ps.StdoutPipe()
defer pipe.Close()
grep.Stdin = pipe
// Run ps first.
ps.Start()
// Run and get the output of grep.
res, _ := grep.Output()
fmt.Println(string(res))
}
Comments
You could do:
out, err := exec.Command("bash", "-c", "ps cax | grep myapp").Output()
answered Dec 8, 2016 at 11:44
Ashwini Chaudhary
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1 Comment
therealak12
You won't be informed about the inner command errors when you use
bash -c. The method that @Nadh suggests has the advantage that if the inner command i.e. ps cax fails and returns non zero value, an error will be returned.In this specific case, you don't really need a pipe, a Go can grep as well:
package main
import (
"bufio"
"bytes"
"os/exec"
"strings"
)
func main() {
c, b := exec.Command("go", "env"), new(bytes.Buffer)
c.Stdout = b
c.Run()
s := bufio.NewScanner(b)
for s.Scan() {
if strings.Contains(s.Text(), "CACHE") {
println(s.Text())
}
}
}
