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In the previous example we looked at
spawning external processes. We
do this when we need an external process accessible to
a running Go process. Sometimes we just want to
completely replace the current Go process with another
(perhaps non-Go) one. To do this we’ll use Go’s
implementation of the classic
exec
function.
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package main
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import (
"os"
"os/exec"
"syscall"
)
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func main() {
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For our example we’ll exec ls. Go requires an
absolute path to the binary we want to execute, so
we’ll use exec.LookPath to find it (probably
/bin/ls).
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binary, lookErr := exec.LookPath("ls")
if lookErr != nil {
panic(lookErr)
}
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Exec requires arguments in slice form (as
opposed to one big string). We’ll give ls a few
common arguments. Note that the first argument should
be the program name.
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args := []string{"ls", "-a", "-l", "-h"}
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Exec also needs a set of environment variables
to use. Here we just provide our current
environment.
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env := os.Environ()
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Here’s the actual syscall.Exec call. If this call is
successful, the execution of our process will end
here and be replaced by the /bin/ls -a -l -h
process. If there is an error we’ll get a return
value.
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execErr := syscall.Exec(binary, args, env)
if execErr != nil {
panic(execErr)
}
}
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