有一个需求是用go语言程序调用外部命令时,允许使用管道符,如 ls | wc -l
Go语言对外部命令的调用进行了一定的封装,下面来试一下:
package main
import (
"os"
"os/exec"
)
func main() {
run1()
}
func run1() {
cmd := exec.Command("ls", "|", "wc", "-l")
cmd.Stdout = os.Stdout
cmd.Stderr = os.Stderr
cmd.Start()
cmd.Run()
cmd.Wait()
}
这样执行时,控制台会打出错误:
ls: 无法访问|: 没有那个文件或目录
ls: 无法访问wc: 没有那个文件或目录
难道Go程序不能使用管道符命令吗?带这此问题,我查了大量的资料,终于发现应该这样写(run2):
package main
import (
"os"
"os/exec"
)
func main() {
// run1()
run2()
}
func run1() {
cmd := exec.Command("ls", "|", "wc", "-l")
cmd.Stdout = os.Stdout
cmd.Stderr = os.Stderr
cmd.Start()
cmd.Run()
cmd.Wait()
}
func run2() {
c1 := exec.Command("ls")
c2 := exec.Command("wc", "-l")
c2.Stdin, _ = c1.StdoutPipe()
c2.Stdout = os.Stdout
c2.Stderr = os.Stderr
c2.Start()
c1.Run()
c2.Wait()
}
哈哈,这样就没问题啦。
下面,我们来点高级的,如查询 nginx 主进行的PID号:
ps -eaf|grep "nginx: master"|grep -v "grep"|awk '{print $2}'(见 run3)
package main
import (
"os"
"os/exec"
)
func main() {
// run1()
// run2()
run3()
}
func run1() {
cmd := exec.Command("ls", "|", "wc", "-l")
cmd.Stdout = os.Stdout
cmd.Stderr = os.Stderr
cmd.Start()
cmd.Run()
cmd.Wait()
}
func run2() {
c1 := exec.Command("ls")
c2 := exec.Command("wc", "-l")
c2.Stdin, _ = c1.StdoutPipe()
c2.Stdout = os.Stdout
c2.Stderr = os.Stderr
c2.Start()
c1.Run()
c2.Wait()
}
func run3() {
c1 := exec.Command("ps", "-eaf")
c2 := exec.Command("grep", `"nginx: master"`)
c3 := exec.Command("grep", "-v", `"grep"`)
c4 := exec.Command("awk", `'{print $2}'`)
c2.Stdin, _ = c1.StdoutPipe()
c3.Stdin, _ = c2.StdoutPipe()
c4.Stdin, _ = c3.StdoutPipe()
c4.Stdout = os.Stdout
c4.Stderr = os.Stderr
c4.Start()
c3.Start()
c2.Start()
c1.Run()
c4.Wait()
}
靠,又不行了,提示:
awk: 1: unexpected character '''
awk: 1: unexpected character '''
它不能支持参数中有引号的内容!
怎么办,难道真的没辙了吗?老天不负有心人,终于被我找到解决办法了,而且更简单:
package main
import (
"os"
"os/exec"
)
func main() {
// run1()
// run2()
// run3()
run4()
}
func run1() {
cmd := exec.Command("ls", "|", "wc", "-l")
cmd.Stdout = os.Stdout
cmd.Stderr = os.Stderr
cmd.Start()
cmd.Run()
cmd.Wait()
}
func run2() {
c1 := exec.Command("ls")
c2 := exec.Command("wc", "-l")
c2.Stdin, _ = c1.StdoutPipe()
c2.Stdout = os.Stdout
c2.Stderr = os.Stderr
c2.Start()
c1.Run()
c2.Wait()
}
func run3() {
c1 := exec.Command("ps", "-eaf")
c2 := exec.Command("grep", `"nginx: master"`)
c3 := exec.Command("grep", "-v", `"grep"`)
c4 := exec.Command("awk", `'{print $2}'`)
c2.Stdin, _ = c1.StdoutPipe()
c3.Stdin, _ = c2.StdoutPipe()
c4.Stdin, _ = c3.StdoutPipe()
c4.Stdout = os.Stdout
c4.Stderr = os.Stderr
c4.Start()
c3.Start()
c2.Start()
c1.Run()
c4.Wait()
}
func run4() {
cmd := exec.Command("/bin/sh", "-c", `ps -eaf|grep "nginx: master"|grep -v "grep"|awk '{print $2}'`)
cmd.Stdout = os.Stdout
cmd.Stderr = os.Stderr
cmd.Start()
cmd.Run()
cmd.Wait()
}
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