| In the previous example we looked at [spawning external processes](spawning-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 <a href="http://en.wikipedia.org/wiki/Exec_(operating_system)"><code>exec</code></a> function. | ||
package main |
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import ( |
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"os" |
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"os/exec" |
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"syscall" |
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) |
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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`). | binary, lookErr := exec.LookPath("ls") |
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if lookErr != nil { |
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panic(lookErr) |
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} |
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| `Exec` requires arguments in slice form (as apposed to one big string). We'll give `ls` a few common arguments. Note that the first argument should be the program name. | args := []string{"ls", "-a", "-l", "-h"} |
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| `Exec` also needs a set of [environment variables](environment-variables) to use. Here we just provide our current environment. | 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. | execErr := syscall.Exec(binary, args, env) |
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if execErr != nil { |
total 4.1M drwxrwxr-x 8 travis travis 4.0K Oct 21 16:50 . drwxrwxr-x 3 travis travis 4.0K Oct 21 16:45 .. drwxrwxr-x 2 travis travis 4.0K Oct 21 16:52 examples drwxrwxr-x 8 travis travis 4.0K Oct 21 16:45 .git -rw-rw-r-- 1 travis travis 33 Oct 21 16:45 .gitignore -rw-rw-r-- 1 travis travis 1.3K Oct 21 16:45 Makefile -rwxrwxr-x 1 travis travis 4.1M Oct 21 16:46 maketable -rw-rw-r-- 1 travis travis 1.8K Oct 21 16:45 README.md drwxrwxr-x 2 travis travis 4.0K Oct 21 16:45 site drwxr-xr-x 2 travis travis 4.0K Oct 21 16:50 subdir drwxrwxr-x 3 travis travis 4.0K Oct 21 16:46 tmp drwxrwxr-x 2 travis travis 4.0K Oct 21 16:45 tools -rw-rw-r-- 1 travis travis 106 Oct 21 16:45 .travis.yml |
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panic(execErr) |
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} |
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} |