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Golang os exec Examples: Command Start and Run
Use the os/exec package, create Commands and use Start and Run on them. Pass arguments to the Command.Os Exec, Command. Often a program needs to start other programs. Not everything can be done in a single Golang program. So we can invoke external processes.
We can import the os/exec package. Then we create a Command with 1 or 2 arguments (we pass the process name, and its arguments in separately).
An example. To begin, we Start a Firefox process. You will need to adjust the path to the Firefox application yourself—on Linux this is firefox-bin.
Start: We call the Start func, and a Firefox window pops upon the computer. Start() does not wait for the process to end.
Golang program that uses Command, Start
package main
import (
"fmt"
"os/exec"
)
func main() {
// Create command.
// ... The application is not executed yet.
cmd := exec.Command("/home/sam/Downloads/firefox/firefox-bin")
fmt.Println("Starting command")
// Run firefox-bin.
// ... This starts a web browser instance.
// It does not wait for it to finish.
cmd.Start()
fmt.Println("DONE")
}
Output
Starting command
DONE
Argument. Here we start an external process with an argument. We pass the argument string to the Command, after the process name itself.
Here: We open Firefox and view Wikipedia's English home page. The next several hours of your time might disappear quickly.
Golang program that uses Command with argument
package main
import (
"fmt"
"os/exec"
)
func main() {
// New command with 1 argument.
browser := "/home/sam/Downloads/firefox/firefox-bin"
argument := "https://en.wikipedia.org/";
cmd := exec.Command(browser, argument)
// Run firefox-bin and load URL specified in argument.
cmd.Start()
fmt.Println("DONE")
}
Output
DONE
Run. Unlike Start, the Run() func waits for the process to end before returning. Here we Run() a Python program. When the program ends, we read its exit value (which is 100 here).
Golang program that uses Command with Run
package main
import (
"fmt"
"os/exec"
)
func main() {
// Run this Python program from Go.
cmd := exec.Command("python", "/home/sam/test.py")
fmt.Println("Running")
// Wait for the Python program to exit.
err := cmd.Run()
fmt.Println("Finished:", err)
}
Output
Running
Finished: exit status 100
Python program:
# This is a Python program.
exit(100)
A summary. With Command, we launch external processes like Firefox and Python (or any EXE or script). We must invoke Start() or Run() to execute the code.
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